Name: experimental methods for spin- and angle-resolved photoemission spectroscopy combined with polarization-variable laser
Uploaded: 2018-06-28T13:00:00.000+00:00
Duration: 9 min
Description: Watch this Scientific Journal Video about Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser at JoVE.com

Wir bedanken uns bei M. Nakayama, S. Toyohisa, A. Fukushima und Y. Ishida für unterstützt, den Versuchsaufbau. Wir dankbar anerkennen, Finanzierung von JSPS Grantin-Hilfe für wissenschaftliche Forschung (B) durch Projekt Nr. 26287061 und für junge Wissenschaftler (B) durch Projekt Nr. 15K 17675. Diese Arbeit wurde auch unterstützt durch MEXT of Japan (innovativer Bereich "topologische Werkstoffwissenschaft," gewähren Nr. 16 H 00979) und JSPS KAKENHI (Grant Nr. 16 H 02209)

1. Probe Montage und Installation
<ol><li>Einkristall Proben von Bi2Se313 in eine ungefähre Größe von 1 × 1 × 0,5 mm geschnitten3 und Nutzung Splitter-basierte Epoxy, die Probe der Probenhalter zu kleben.</li>
	<li>Fügen Sie das Klebeband auf der Probenoberfläche. Hinweis: Das tesaband dient zum Spalten der Probe in ultrahigh Vakuumkammer (UHV) eine atomar saubere Oberfläche zu erhalten.</li>
	<li>Installieren Sie des Beispiels in die Probe Magazin in die Last-Sperre, und starten Sie die Pumpe, bis der Druck des Schlosses Last niedriger als 1 × 10-5 PA.</li>
</ol>2. Beispiel Spalten
<ol><li>Öffnen Sie das UHV-Ventil zwischen der Last-Schloss und der UHV-Vorbereitung-Kammer.</li>
	<li>Verschieben Sie das Probe-Magazin aus dem Last-Felsen Vorbereitung Kammer mithilfe der linearen/Rotary Durchführung die Schleusenkammer Last befestigt ist.</li>
	<li>Abholen der Probe aus der Probe Magazin von der Transfer-Rod an der Vorbereitung Kammer angebracht.</li>
	<li>Wieder das Beispiel Magazin ins Last Schloss und schließen Sie UHV Ventil.</li>
	<li>Warten Sie, bis der Druck der Vorbereitung Kammer unterhalb 5 × 10-7 PA.</li>
	<li>Schälen Sie das tesaband Wobble Stick in der Vorbereitung-Kammer mit und Spalten Sie die Probe unter der UHV-Bedingung.</li>
</ol>(3) Probentransfer, die Messposition
<ol><li>Übertragen Sie die Probe auf die UHV-Messkammer, und beheben Sie die Probe Gonio-Hauptbühne durch den Schraubenzieher mit der Messkammer ausgestattet.</li>
	<li>Verschieben Sie die Gonio-Phase, die Messposition und genau Probenposition auf den Schwerpunkt des Spektrometers verschieben mithilfe der Mikrometer-Bühne.</li>
</ol>4. 7eV-Laser-Setup
<ol><li>Schalten Sie die Nd:YVO4-Laser. Hinweis: Der Laser erzeugt 355 nm Laserlicht mit einer hohen Wiederholungsrate von 120 MHz.</li>
	<li>Den Laser-Strahl-Verschluss zu öffnen, und sicherstellen, dass der Laser die KBBF Kristall und eine zweite harmonische Welle von 177 durchläuft nm (6,994 eV) generiert.</li>
	<li>Optimieren Sie die Leistung des 7eV-Lasers durch eine Änderung der Leistung des Lasers mit der Variable Abschwächer 355 nm.</li>
</ol>5. ARPES Datenerfassung
<ol><li>Die Analysator Steuerungssoftware auf dem Desktop-Computer zu öffnen. Hinweis: Wir verwenden "SES-Software", die ein allgemeines Programm für steuernde ScientaOmicron Analyzer mit einem Elektron-Deflektor ist.</li>
	<li>Wählen Sie Setup... unter Sequenz im Menü bar (Bild 2, Schritt i. 2-1).</li>
	<li>Wählen Sie ARPES Konfiguration (Abbildung 3, Schritt i. 3-1) und ARPES Mapping in der Liste (Abbildung 3, Schritt i. 3-2) zur Durchführung Fermi Oberfläche Zuordnung mit dem Photoelektronen-Deflektor.</li>
	<li>Klicken Sie auf Bearbeiten (Abbildung 3, Schritt i. 3-3) und konfigurieren Sie Fermi Oberfläche Zuordnung von-12 ° bis 12 ° ein Emissionswinkel θy mit Schrittweite von 0,5 ° (Abbildung 3, Schritt i. 3-4). Hinweis: Der halbkugelförmige Analyzer mit einem Elektron-Deflektor ermöglicht uns die Fermi Oberfläche ohne die Probe Rotationen zuordnen.</li>
	<li>Klicken Sie auf Ausführen (Abbildung 2, Schritt i. 2-3).</li>
</ol>6. SARPES Datenerfassung
<ol><li>Manuell ändern der Maschineneinstellung zur SARPES Messung einschließlich der Analysator Einlauföffnung und Maschenweite (Abbildung 1).</li>
	<li>Wählen Sie Setup... unter Sequenz im Menü bar (Bild 2, Schritt i. 2-2).</li>
	<li>Wählen Sie Konfiguration drehen (Abbildung 4, Schritt i. 4-1) und Normal in der Liste (Abbildung 4, Schritt i. 4-2), und klicken Sie auf "OK" (Abbildung 4, Schritt i. 4-3).</li>
	<li>DA30 (Abbildung 5, Schritt i. 5-1) auf die Menüleiste und Kontrolle Thetaauswählen... (Abbildung 5, Schritt i. 5-2) um die Einstellung für die DA30 Winkel (θX, θy) Konfiguration zu öffnen.</li>
	<li>Wählen Sie den Emissionswinkel (θX, θy) = (-6 °, 0 ° c) zu SARPES Spektren (Abbildung 5, Schritt i. 5-3).</li>
	<li>Magnetisches Feld durch die Kontrolle der bipolaren Kondensator-Bank um das VLEED Ziel in positiver Richtung entlang der bestimmten Achse magnetisieren gelten (α: X, yoder Z). Hinweis: In unserem System kann dieser Prozess über Eingabeaufforderung [Abb. 6 (a)] erfolgen.</li>
	<li>Klicken Sie auf Ausführen , um Intensität Spektrum (Abbildung 2, Schritt i. 2-3) zu nehmen.</li>
	<li>Legen Sie Magnetfeld um das VLEED Ziel in negativer Richtung entlang α zu magnetisieren und Scan Intensität Spektrum zu starten.</li>
	<li>Berechnen der Spinpolarisation und die Spin-gelöst-Spektren.</li>
</ol>7. Scannen die Lichtpolarisation Abhängigkeit
<ol><li>Ändern Sie den Winkel der λ/2-Waveplate exakt gesteuert durch die Schrittmotor Tune die Lichtpolarisation des 7 eV-Lasers. Hinweis: In unserem System kann dieser Prozess über Eingabeaufforderung [Abb. 6 (b)] erfolgen.</li>
	<li>Nehmen Sie die Drehung gelöst Spektren für X, y und Z -Achsen.</li>
	<li>Scannen Sie die Drehung gelöst Spektren als Funktion der Lichtpolarisation mit den halben Waveplate Winkel von 0° bis 102° mit Schrittweite von 3°.</li>
</ol>

<ol>
	<li>Damascelli, A., Hussain, Z., Shen, Z. -. X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Angle-resolved+photoemission+studies+of+the+cuprate+superconductors.">Angle-resolved photoemission studies of the cuprate superconductors.</a> Rev. Mod. Phys. 75 (2), 473-541 (2003).</li><li>Qiao, S., Kimura, A., Harasawa, A., Sawada, M., Chung, J. -. G., Kakizaki, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+compact+electron+spin+polarimeter+with+a+high+efficiency.">A new compact electron spin polarimeter with a high efficiency.</a> Rev. Sci. Instrum. 68 (12), 4390-4395 (1997).</li><li>Dil, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spin+and+angle+resolved+photoemission+on+non-magnetic+low-dimensional+systems.">Spin and angle resolved photoemission on non-magnetic low-dimensional systems.</a> J. Phys. Condens. Matter. 21 (40), 403001 (2009).</li><li>Hoesch, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spin-polarized+Fermi+surface+mapping.">Spin-polarized Fermi surface mapping.</a> J. Electron Spectrosc. 124 (2), 263-279 (2002).</li><li>Souma, S., Takayama, S., Sugawara, K., Sato, T., Takahashi, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrahigh-resolution+spin-resolved+photoemission+spectrometer+with+a+mini+Mott+detector.">Ultrahigh-resolution spin-resolved photoemission spectrometer with a mini Mott detector.</a> Rev. Sci. Instrum. 81 (9), 096101 (2010).</li><li>Okuda, T., Kimura, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spin-+and+angle-resolved+photoemission+of+strongly+spin-orbit+coupled+systems.">Spin- and angle-resolved photoemission of strongly spin-orbit coupled systems.</a> J. Phys. Soc. Jpn. 82 (2), 021002 (2013).</li><li>Okuda, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+spin-polarized+photoemission+spectrometer+with+very+high+efficiency+and+energy+resolution.">A new spin-polarized photoemission spectrometer with very high efficiency and energy resolution.</a> Rev. Sci. Instrum. 79 (12), 123117 (2008).</li><li>Jozwiak, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+high-efficiency+spin-resolved+photoemission+spectrometer+combining+time-of-flight+spectroscopy+with+exchange-scattering+polarimetry.">A high-efficiency spin-resolved photoemission spectrometer combining time-of-flight spectroscopy with exchange-scattering polarimetry.</a> Rev. Sci. Instrum. 81 (5), 053904 (2010).</li><li>Okuda, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficient+spin+resolved+spectroscopy+observation+machine+at+Hiroshima+Synchrotron+Radiation+Center.">Efficient spin resolved spectroscopy observation machine at Hiroshima Synchrotron Radiation Center.</a> Rev. Sci. Instrum. 82 (10), 103302 (2011).</li><li>Yaji, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-resolution+three-dimensional+spin-+and+angle-resolved+photoelectron+spectrometer+using+vacuum+ultraviolet+laser+light.">High-resolution three-dimensional spin- and angle-resolved photoelectron spectrometer using vacuum ultraviolet laser light.</a> Rev. Sci. Instrum. 87 (5), 053111 (2016).</li><li>Shimojima, T., Okazaki, K., Shin, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Low-temperature+and+high-energy-resolution+laser+photoemission+spectroscopy.">Low-temperature and high-energy-resolution laser photoemission spectroscopy.</a> J. Phys. Soc. Jpn. 84 (7), 072001 (2015).</li><li>Augustine, S., Mathai, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Growth,+morphology,+and+microindentation+analysis+of+Bi2Se3,+Bi1.8In0.2Se3,+and+Bi2Se2.8Te0.2+single+crystals.">Growth, morphology, and microindentation analysis of Bi2Se3, Bi1.8In0.2Se3, and Bi2Se2.8Te0.2 single crystals.</a> Mater. Res. Bull. 36 (13), 2251-2261 (2001).</li><li>Hasan, M. Z., Kane, C. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Colloquium:+Topological+insulators.">Colloquium: Topological insulators.</a> Rev. Mod. Phys. 82 (4), 3045-3067 (2010).</li><li>Ando, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Topological+insulator+materials.">Topological insulator materials.</a> J. Phys. Soc. Jpn. 82 (10), 102011 (2013).</li><li>Zhang, H., Liu, C. -. X., Qi, X. -. L., Dai, X., Fang, Z., Zhang, S. -. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Topological+insulators+in+Bi2Se3,+Bi2Te3+and+Sb2Te3+with+a+single+Dirac+cone+on+the+surface.">Topological insulators in Bi2Se3, Bi2Te3 and Sb2Te3 with a single Dirac cone on the surface.</a> Nature Phys. 5 (6), 438-442 (2009).</li><li>Cao, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mapping+the+orbital+wavefunction+of+the+surface+states+in+three-dimensional+topological+insulators.">Mapping the orbital wavefunction of the surface states in three-dimensional topological insulators.</a> Nature Phys. 9 (8), 499-504 (2013).</li><li>Zhang, H., Liu, C. -. X., Zhang, S. -. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spin-orbital+texture+in+topological+insulators.">Spin-orbital texture in topological insulators.</a> Phys. Rev. Lett. 111 (6), 066801 (2013).</li><li>Kuroda, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coherent+control+over+three-dimensional+spin-polarization+for+the+spin-orbit+coupled+surface+state+of+Bi2Se3.">Coherent control over three-dimensional spin-polarization for the spin-orbit coupled surface state of Bi2Se3.</a> Phys. Rev. B. 94 (16), 165162 (2016).</li><li>Meier, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interference+of+spin+states+in+photoemission+from+Sb/Ag(111)+surface+alloys.">Interference of spin states in photoemission from Sb/Ag(111) surface alloys.</a> J Phys-Condens Mat. 23 (7), 072207 (2011).</li><li>Dil, J. H., Meier, F., Osterwalder, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rashba-type+spin+splitting+and+spin+interference+of+the+Cu(111)+surface+state+at+room+temperature.">Rashba-type spin splitting and spin interference of the Cu(111) surface state at room temperature.</a> J Electron Spectrosc. 201, 42-46 (2015).</li><li>Yaji, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spin-dependent+quantum+interference+in+photoemission+process+from+spin-orbit+coupled+states.">Spin-dependent quantum interference in photoemission process from spin-orbit coupled states.</a> Nature Commun. 8, 14588 (2017).</li><li>Noguchi, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+mapping+of+spin+and+orbital+entangled+wave+functions+under+interband+spin-orbit+coupling+of+giant+Rashba+spin-split+surface+states.">Direct mapping of spin and orbital entangled wave functions under interband spin-orbit coupling of giant Rashba spin-split surface states.</a> Phys. Rev. B. 95 (6), 04111(R) (2017).</li></ol>

Die Autoren erklären, dass sie keine finanziellen Interessenkonflikte.

ARPES und SARPES Techniken wurden häufig verwendet für das Studium der elektronischen Bandstrukturen durch die Zuordnung von Band und Spin-Erkennung1,2. Neben diesen allgemeinen Vorteilen, die oben gezeigt kann Laser-SARPES basierend auf orbital Auswahlregel in optischen Dipol Erregung als eine neuartige Technik zur Visualisierung des Spin-Orbital-Kupplung-Effekts in der Wellenfunktion und Quantum Spin Eingriff eingesetzt werden . Wie in Ab...

Winkel gelöst fotoemission Spektroskopie (ARPES) Technik entwickelte sich zu einer der mächtigsten Werkzeug Bandstrukturen Quasiteilchen in Festkörpern1zu untersuchen. Die meisten von attraktive Eigenschaft der ARPES ist die Fähigkeit zur Band-Mapping, um elektronische Staaten im Energie- und Impulserhaltung Raum charakterisieren. Spin-resolved ARPES (SARPES), die hier mit Spin-Detektoren, z.B.ausgestattet ist. Mott-Detektor2,3, weitere ermöglicht es uns, den Spin-Charakter der beobachteten Band Strukturen4zu lösen. Da der Mott-Detektor die Spin mit zwei Achsen (X und Zoder y und Z) messen kann, ermöglicht die Kombination der beiden Mott Detektoren weiter Spin-Orientierung in drei Dimensionen4,5 zu erhalten . Seit mehreren Jahrzehnten jedoch die SARPES Experimente waren litt ihre geringe Effizienz (in der Regel 1/10000 im Vergleich dazu für Spin-integrierte ARPES Messung)3,4,5,6 ,7, die die Energie und eckige Auflösung begrenzt hatte. Vor kurzem wurde die Energieauflösung von SARPES mit einem hocheffizienten Spin-Detektor basierend auf Exchange-Streuung, die so genannte sehr-niedrig-Energie-Elektronenbeugung (VLEED) Detektor7,8,9 erhöht ,10. Mit diesem Detektor die Datenqualität wurde deutlich verbessert und die Daten Akquisition verkürzt. Vor kurzem gelungen, SARPES stark um Spin-polarisierten elektronische Staaten und vor allem Spin-Bahn Kopplung Effekts in der Spin-Textur der Oberfläche Bands7zu beheben.
Hier beschäftigen wir SARPES Messungen mit einer Polarisation-Variable Vakuum-Ultraviolett laser-Licht (Laser-SARPES) und die großen Vorteile dieser kombinierten Technik zu demonstrieren. Durch die Untersuchung auf die Spin-Bahn-Verbindung Oberfläche Staaten Bi2Se3präsentieren wir Ihnen zwei Möglichkeiten der Laser-SARPES. Erstens wegen der orbital Auswahlregel linear polarisierten Laser in Dipol Übergang Regime, p- und s-polarisiertes Licht selektiv begeistern einen Teil des Eigen-Wellenfunktionen mit verschiedenen orbitalen Symmetrie. Solch eine orbitale selektive Anregung gibt es dabei in SARPES, nämlich Orbital-selektive SARPES. Zweitens, dreidimensionale (3D) Spin-Erfassung in SARPES zeigt die Richtung der Drehachse Quanten und direkt zeigt vollständige Informationen über die Licht-Polarisation-Abhängigkeit. In diesem Protokoll beschreiben wir kurz eine Methodik um diese State-of-the-Art Laser-SARPES Technik um die starken Spin-Bahn Kopplung Auswirkungen zu studieren.
Unsere Laser-SARPES-System befindet sich am Institut für Festkörperphysik, The University of Tokyo11. Die schematische Zeichnung unserer Laser-SAPRES-Maschine ist in Abbildung 1dargestellt. Die Polarisation-Variable 7-eV Laser Licht12 erhellt die Probenoberfläche und der Photoelektronen werden aus der Probe abgegeben. Die Polarisation der Laser automatisch gesteuert MgF2- basierte λ/2- und λ/4-wellenplatten, lineare und zirkularen Polarisationen selektiv zu verwenden. Eine halbkugelförmige Elektron-Analysator korrigiert die Photoelektronen und analysiert ihre kinetische Energie (EKin) und Emissionswinkel (θX und θy). Die Photoelektronen Intensitäten werden auf der EKin-θX Bildschirm überwacht von einer CCD-Kamera abgebildet. Dieses Bild wird direkt in die Energie-Bandstruktur im reziproken Raum umgewandelt.
Für SARPES Messung der Photoelektronen mit einem bestimmten Abstrahlwinkel und die kinetische Energie von den Elektronen-Analyzer analysiert orientieren sich an zwei VLEED-Typ-Spin-Detektoren mit einem 90-Grad-Photoelektronen-Deflektor und Photoelektronen Balken konzentrieren sich auf zwei verschiedene Ziele der Fe(001) -p(1 × 1) Filme von Sauerstoff gekündigt. Die Photoelektronen reflektierten die Ziele werden in einzelne Kanalerkennung erkannt, mithilfe einer Channeltrons in jeder Spin-Detektor gelegt. Die VLEED Ziele können mit Helmholtz-Typ elektrische Spulen magnetisiert werden, die mit orthogonalen Geometrie zueinander angeordnet sind. Die Magnetisierungsrichtung der bipolaren Kondensator-Bank gesteuert. Die doppelte VLEED Spin-Detektoren ermöglichen dabei den Spinpolarisation Vektor der Photoelektronen in drei Dimensionen zu analysieren.

<table><tbody><tr><td>DA30-L hemispherical analyzer</td><td>ScientaOmicron</td><td></td><td>http://www.scientaomicron.com/en/products/353/1170</td></tr><tr><td>Silver-based epoxy</td><td>Epoxy Technology</td><td>H20E</td><td></td></tr><tr><td>Sctoch tape</td><td>3M</td><td>801-1-18C</td><td></td></tr><tr><td>UHV valve</td><td>VAT</td><td>01034-KE01</td><td></td></tr><tr><td>linear/rotary feedthrough</td><td>Ferrovac</td><td>MD40</td><td></td></tr><tr><td>transfer rod</td><td>UHV design</td><td>PP series</td><td></td></tr><tr><td>wobble stick</td><td>Ferrovac</td><td>WM40</td><td></td></tr><tr><td>Paladin compact 355</td><td>Coherent</td><td></td><td></td></tr><tr><td>half waveplate</td><td>Kogakugiken</td><td></td><td>order made</td></tr><tr><td>Bipolar condenser bank</td><td>Tsuji electronics</td><td></td><td></td></tr></tbody></table>

experimental methods for spin- and angle-resolved photoemission spectroscopy combined with polarization-variable laser

Das Ziel dieses Protokolls ist zu präsentieren wie Spin und Winkel gelöst fotoemission Spektroskopie kombiniert mit Polarisation-Variable 7-eV Laser (Laser-SARPES) durchgeführt, und eine Leistung von dieser Technik für das Studium der Festkörperphysik zu demonstrieren. Laser-SARPES erreicht zwei große Fähigkeiten. Erstens kann durch die Untersuchung orbital Auswahlregel linear polarisierten Laser, orbital selektive Anregung in SAPRES Experiment durchgeführt werden. Zweitens kann die Technik umfassend eine Variation der Quanten Drehachse in Abhängigkeit von der Lichtpolarisation zeigen. Um die Leistungsfähigkeit der Zusammenarbeit dieser Funktionen in Laser-SARPES demonstrieren, wenden wir diese Technik für die Untersuchungen der Spin-Bahn-Verbindung Oberfläche Staaten Bi2Se3. Diese Technik bietet, Spin und Orbital-Komponenten aus der Spin-Bahn-Verbindung-Wellenfunktionen zu zerlegen. Darüber, wie ein repräsentative Vorteil bei der Verwendung der direkten Spin-Erkennung mit der Polarisation-Variable Laser zusammenarbeitete, visualisiert die Technik eindeutig die Lichtpolarisation Abhängigkeit der Quanten Drehachse in drei Dimension. Laser-SARPES steigt dramatisch an eine Fähigkeit der Photonenemission Technik.

Bevor Sie beginnen SARPES Experimente, müssen k Positionen genau bestimmt werden, für die Aufnahme von Spin gelöst Spektrum mit hohen statistischen Spin-integrierte ARPES Ergebnisse mit hoher Energie - und kantig-Auflösungen (Protokoll 5.1-5.5). Dies wird in Abbildung 7 gezeigt, wo die ARPES Ergebnisse für eine Bi-2Se3 Einkristall vorgestellt werden. Dieses Material ist als prototypische topologischer Isolator mit einem Spi...

Watch this Scientific Journal Video about Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser at JoVE.com

Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser

Hier kombinieren wir Polarisation-Variable 7-eV Laser mit Spin und Winkel gelöst fotoemission Technik, die Spin-Orbital Kupplung Wirkung in Festkörpern zu visualisieren.

Experimentelle Methoden für Spin - und Winkel-Resolved Photoemission Spectroscopy kombiniert mit Polarisation-Variable Laser

The goal of this protocol is to present how to perform spin- and angle-resolved photoemission spectroscopy combined with polarization-variable 7-eV laser ...

experimental-methods-for-spin-angle-resolved-photoemission

Universidad San Sebastian

Research

JoVE Journal

Engineering

9.8K Aufrufe.  University of Tokyo. Hier kombinieren wir Polarisation-Variable 7-eV Laser mit Spin und Winkel gelöst fotoemission Technik, die Spin-Orbital Kupplung Wirkung in Festkörpern zu visualisieren.

Serie: Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser

Angle-resolved Photoemission Spectroscopy At Ultra-low Temperatures

The physical properties of a material are defined by its electronic structure. Electrons in solids are characterized by energy (&omega;) and momentum (k) and the probability to find them in a particular state with given &omega; and k is described by the spectral function A(k, &omega;). This function can be directly measured in an experiment based on the well-known photoelectric effect, for the explanation of which Albert Einstein received the Nobel Prize back in 1921. In the photoelectric effect the light shone on a surface ejects electrons from the material. According to Einstein, energy conservation allows one to determine the energy of an electron inside the sample, provided the energy of the light photon and kinetic energy of the outgoing photoelectron are known. Momentum conservation makes it also possible to estimate k relating it to the momentum of the photoelectron by measuring the angle at which the photoelectron left the surface. The modern version of this technique is called Angle-Resolved Photoemission Spectroscopy (ARPES) and exploits both conservation laws in order to determine the electronic structure, i.e. energy and momentum of electrons inside the solid. In order to resolve the details crucial for understanding the topical problems of condensed matter physics, three quantities need to be minimized: uncertainty* in photon energy, uncertainty in kinetic energy of photoelectrons and temperature of the sample.
In our approach we combine three recent achievements in the field of synchrotron radiation, surface science and cryogenics. We use synchrotron radiation with tunable photon energy contributing an uncertainty of the order of 1 meV, an electron energy analyzer which detects the kinetic energies with a precision of the order of 1 meV and a He3 cryostat which allows us to keep the temperature of the sample below 1 K. We discuss the exemplary results obtained on single crystals of Sr2RuO4 and some other materials. The electronic structure of this material can be determined with an unprecedented clarity.

The overall goal of this method is to determine the low-energy electronic structure of solids at ultra-low temperatures using Angle-Resolved Photoemission Spectroscopy with synchrotron radiation.

Angle-Photoemissionsspektroskopie Bei extrem niedrigen Temperaturen

The physical properties of a material are defined by its  electronic structure. Electrons in solids are characterized by energy (&omega;)  and momentum ...

Forschung

Ingenieurwesen

Automation of Mode Locking in a Nonlinear Polarization Rotation Fiber Laser through Output Polarization Measurements

When a laser is mode-locked, it emits a train of ultra-short pulses at a repetition rate determined by the laser cavity length. This article outlines a new and inexpensive procedure to force mode locking in a pre-adjusted nonlinear polarization rotation fiber laser. This procedure is based on the detection of a sudden change in the output polarization state when mode locking occurs. This change is used to command the alignment of the intra-cavity polarization controller in order to find mode-locking conditions. More specifically, the value of the first Stokes parameter varies when the angle of the polarization controller is swept and, moreover, it undergoes an abrupt variation when the laser enters the mode-locked state. Monitoring this abrupt variation provides a practical easy-to-detect signal that can be used to command the alignment of the polarization controller and drive the laser towards mode locking. This monitoring is achieved by feeding a small portion of the signal to a polarization analyzer measuring the first Stokes parameter. A sudden change in the read out of this parameter from the analyzer will occur when the laser enters the mode-locked state. At this moment, the required angle of the polarization controller is kept fixed. The alignment is completed. This procedure provides an alternate way to existing automating procedures that use equipment such as an optical spectrum analyzer, an RF spectrum analyzer, a photodiode connected to an electronic pulse-counter or a nonlinear detecting scheme based on two-photon absorption or second harmonic generation. It is suitable for lasers mode locked by nonlinear polarization rotation. It is relatively easy to implement, it requires inexpensive means, especially at a wavelength of 1550 nm, and it lowers the production and operation costs incurred in comparison to the above-mentioned techniques.

A protocol to detect and automate mode locking in a pre-adjusted nonlinear polarization rotation fiber laser is presented. The detection of a sudden change in the output polarization state when mode locking occurs is used to command the alignment of an intra-cavity polarization controller in order to find mode-locking conditions.

Automatisierung der Modenkopplung in einem nicht-linearen Polarisationsdrehung Faserlaser durch Ausgabe Polarisationsmessungen

When a laser is mode-locked, it emits a train of ultra-short pulses at a repetition rate determined by the laser cavity length. This article outlines a ...

High Resolution Phonon-assisted Quasi-resonance Fluorescence Spectroscopy

High resolution optical spectroscopy methods are demanding in terms of either technology, equipment, complexity, time or a combination of these. Here we demonstrate an optical spectroscopy method that is capable of resolving spectral features beyond that of the spin fine structure and homogeneous linewidth of single quantum dots (QDs) using a standard, easy-to-use spectrometer setup. This method incorporates both laser and photoluminescence spectroscopy, combining the advantage of laser line-width limited resolution with multi-channel photoluminescence detection. Such a scheme allows for considerable improvement of resolution over that of a common single-stage spectrometer. The method uses phonons to assist in the measurement of the photoluminescence of a single quantum dot after resonant excitation of its ground state transition. The phonon&#39;s energy difference allows one to separate and filter out the laser light exciting the quantum dot. An advantageous feature of this method is its straight forward integration into standard spectroscopy setups, which are accessible to most researchers.

The manuscript describes a method of phonon-assisted quasi-resonant fluorescence spectroscopy that incorporates both laser-limited resolution and photoluminescence (PL) spectroscopy. This method utilizes optical phonons to provide linewidth-limited resolution spectra of atom-like semiconductor structures in the energy domain. The method is also easily realized with a single spectrometer optical spectroscopy setup.

Hohe Auflösung Phonon-unterstützte Quasi- Resonanzfluoreszenzspektroskopie

High resolution optical spectroscopy methods are demanding in terms of either technology, equipment, complexity, time or a combination of these. Here we ...

Direct Imaging of Laser-driven Ultrafast Molecular Rotation

We present a method for visualizing laser-induced, ultrafast molecular rotational wave packet dynamics. We have developed a new 2-dimensional Coulomb explosion imaging setup in which a hitherto-impractical camera angle is realized. In our imaging technique, diatomic molecules are irradiated with a circularly polarized strong laser pulse. The ejected atomic ions are accelerated perpendicularly to the laser propagation. The ions lying in the laser polarization plane are selected through the use of a mechanical slit and imaged with a high-throughput, 2-dimensional detector installed parallel to the polarization plane. Because a circularly polarized (isotropic) Coulomb exploding pulse is used, the observed angular distribution of the ejected ions directly corresponds to the squared rotational wave function at the time of the pulse irradiation. To create a real-time movie of molecular rotation, the present imaging technique is combined with a femtosecond pump-probe optical setup in which the pump pulses create unidirectionally rotating molecular ensembles. Due to the high image throughput of our detection system, the pump-probe experimental condition can be easily optimized by monitoring a real-time snapshot. As a result, the quality of the observed movie is sufficiently high for visualizing the detailed wave nature of motion. We also note that the present technique can be implemented in existing standard ion imaging setups, offering a new camera angle or viewpoint for the molecular systems without the need for extensive modification.

We present a protocol for creating a real-time movie of a molecular rotational wave packet using a high-resolution Coulomb explosion imaging setup.

Direct Imaging von lasergetriebenen Ultrakurz Molecular Rotation

We present a method for visualizing laser-induced, ultrafast molecular rotational wave packet dynamics. We have developed a new 2-dimensional Coulomb ...

Chemie

Determination of the Excitation and Coupling Rates Between Light Emitters and Surface Plasmon Polaritons

We have developed a unique method to measure the excitation and coupling rates between the light emitters and surface plasmon polaritons (SPPs) arising from metallic periodic arrays without involving time-resolved techniques. We have formulated the rates by quantities that can be measured by simple optical measurements. The instrumentation based on angle- and polarization-resolved reflectivity and photoluminescence spectroscopy will be described in detail here. Our approach is intriguing due to its simplicity, which requires routine optics and several mechanical stages, and thus is highly affordable to most of the research laboratories.

This protocol describes the instrumentation for determining the excitation and coupling rates between light emitters and Bloch-like surface plasmon polaritons arising from periodic arrays.

Bestimmung der Erregung und Kupplung zwischen Lichtemittern und Oberflächen Plasmon Polaritonen

We have developed a unique method to measure the excitation and coupling rates between the light emitters and surface plasmon polaritons (SPPs) arising ...

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F&#8722;

Anion photoelectron imaging is a very efficient method for the study of energy states of bound negative ions, neutral species and interactions of unbound electrons with neutral molecules/atoms. State-of-the-art in vacuo anion generation techniques allow application to a broad range of atomic, molecular, and cluster anion systems. These are separated and selected using time-of-flight mass spectrometry. Electrons are removed by linearly polarized photons (photo detachment) using table-top laser sources which provide ready access to excitation energies from the infra-red to the near ultraviolet. Detecting the photoelectrons with a velocity mapped imaging lens and position sensitive detector means that, in principle, every photoelectron reaches the detector and the detection efficiency is uniform for all kinetic energies. Photoelectron spectra extracted from the images via mathematical reconstruction using an inverse Abel transformation reveal details of the anion internal energy state distribution and the resultant neutral energy states. At low electron kinetic energy, typical resolution is sufficient to reveal energy level differences on the order of a few millielectron-volts, i.e., different vibrational levels for molecular species or spin-orbit splitting in atoms. Photoelectron angular distributions extracted from the inverse Abel transformation represent the signatures of the bound electron orbital, allowing more detailed probing of electronic structure. The spectra and angular distributions also encode details of the interactions between the outgoing electron and the residual neutral species subsequent to excitation. The technique is illustrated by the application to an atomic anion (F&#8722;), but it can also be applied to the measurement of molecular anion spectroscopy, the study of low lying anion resonances (as an alternative to scattering experiments) and femtosecond (fs) time resolved studies of the dynamic evolution of anions.

Here, we present a protocol for photoelectron imaging of anionic species. Anions generated in vacuo and separated by mass spectrometry are probed using velocity mapped photoelectron imaging, providing details of anion and neutral energy levels, anion and neutral structure and the nature of the anion electronic state.

Photoelektronen Bildgebung von Anionen illustriert von 310 Nm Ablösung der F−

Anion photoelectron imaging is a very efficient method for the study of energy states of bound negative ions, neutral species and interactions of unbound ...

A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference

We present a high-performance source of unconditional polarization-entangled photons that have a high-emission rate, a broadband distribution, are degenerated and postselection free. The property of the source is based on the multiple quantum interference effect with a round-trip configuration of a Sagnac interferometer. The quantum interference effects make it possible to use the high generation efficiency of the polarization-entangled photons to process parametric down-conversion, and separate degenerated photon pairs into different optical modes without a postselection requirement. The principle of the optical system was described and experimentally used to measure the fidelity and Bell parameters, and also to characterize the generated polarization-entangled photons from a minimum of six combinations of polarization correlated data. The experimentally obtained fidelity and Bell parameters exceeded the classical local correlation limit and are clear evidence of the generation of unconditional polarization-entangled photons.

We describe an optical system for the generation of unconditional polarization-entangled photons based on multiple quantum interference effects with a detection scheme to estimate the experimental fidelity of generated entangled photons.

Ein photonisches System zur Erzeugung bedingungsloser Polarisations-verwirrter Photonen basierend auf multipler Quanteninterferenz

We present a high-performance source of unconditional polarization-entangled photons that have a high-emission rate, a broadband distribution, are ...

Spectral and Angle-Resolved Magneto-Optical Characterization of Photonic Nanostructures

Photonic crystals are periodic nanostructures that can support a variety of confined electromagnetic modes. Such confined modes are usually accompanied by local enhancement of electric field intensity that strengthens light-matter interactions, enabling applications such as surface-enhanced Raman scattering (SERS) and surface plasmon enhanced sensing. In the presence of magneto-optically active materials, the local field enhancement gives rise to anomalous magneto-optical activity. Typically, the confined modes of a given photonic crystal depend strongly on the wavelength and incidence angle of the incident electromagnetic radiation. Thus, spectral and angular-resolved measurements are needed to fully identify them as well as to establish their relationship with the magneto-optical activity of the crystal. In this article, we describe how to use a Fourier-plane (back focal plane) microscope to characterize magneto-optically active samples. As a model system, here we use a plasmonic grating built out of magneto-optically active Au/Co/Au multilayer. In the experiments, we apply a magnetic field on the grating in situ and measure its reciprocal space response, obtaining the magneto-optical response of the grating over a range of wavelengths and incident angles. This information enables us to build a complete map of the plasmonic band structure of the grating and the angle and wavelength dependent magneto-optical activity. These two images allow us to pinpoint the effect that the plasmon resonances have on the magneto-optical response of the grating. The relatively small magnitude of magneto-optical effects requires a careful treatment of the acquired optical signals. To this end, an image processing protocol for obtaining magneto-optical response from the acquired raw data is laid out.

Photonic band structure enables understanding how confined electromagnetic modes propagate within a photonic crystal. In photonic crystals that incorporate magnetic elements, such confined and resonant optical modes are accompanied by enhanced and modified magneto-optical activity. We describe a measurement procedure to extract the magneto-optical band structure by Fourier space microscopy.

Spektrale und winkelaufgelöste magneto-optische Charakterisierung photoischer Nanostrukturen

Photonic crystals are periodic nanostructures that can support a variety of confined electromagnetic modes. Such confined modes are usually accompanied by ...

In Situ Measurement of Vacuum Window Birefringence using 25Mg+ Fluorescence

Accurate control of the polarization states of laser light is important in precision measurement experiments. In experiments involving the use of a vacuum environment, the stress-induced birefringence effect of the vacuum windows will affect the polarization states of laser light inside the vacuum system, and it is very difficult to measure and optimize the polarization states of the laser light in situ. The purpose of this protocol is to demonstrate how to optimize the polarization states of the laser light based on the fluorescence of ions in the vacuum system, and how to calculate the birefringence of vacuum windows based on azimuthal angles of external wave plates with Mueller matrix. The fluorescence of 25Mg+ ions induced by laser light that is resonant with the transition of |32P3/2,F = 4, mF&#160;= 4<img align="center" alt="Equation 100" src="/files/ftp_upload/61175/61175img1.jpg" style="color: rgb(68, 0, 68); font-size: 18px; font-weight: 700;" />&#160;&#8594;&#160;|32S1/2,F = 3, mF&#160;= 3<img align="center" alt="Equation 100" src="/files/ftp_upload/61175/61175img1.jpg" style="color: rgb(68, 0, 68); font-size: 18px; font-weight: 700;" />&#160;is sensitive to the polarization state of the laser light, and maximum fluorescence will be observed with pure circularly polarized light. A combination of half-wave plate (HWP) and quarter-wave plate (QWP) can achieve arbitrary phase retardation and is used for compensating the birefringence of the vacuum window. In this experiment, the polarization state of the laser light is optimized based on the fluorescence of 25Mg+ ion with a pair of HWP and QWP outside the vacuum chamber. By adjusting the azimuthal angles of the HWP and QWP to obtain maximum ion fluorescence, one can obtain a pure circularly polarized light inside the vacuum chamber. With the information on the azimuthal angles of the external HWP and QWP, the birefringence of the vacuum window can be determined.

In Situ Measurement of Vacuum Window Birefringence using 25Mg+ Fluorescence

Presented here is a method to measure the birefringence of vacuum windows by maximizing the fluorescence counts emitted by Doppler cooled 25Mg+ ions in an ion trap. The birefringence of vacuum windows will change the polarization states of the laser, which can be compensated by changing the azimuthal angles of external wave plates.

In Situ Messung der Vakuumfenster-Birefabenz mit 25Mg+ Fluoreszenz

Accurate control of the polarization states of laser light is important in precision measurement experiments. In experiments involving the use of a vacuum ...

Charakterisierung von Sphärolithen mit polarisationsempfindlicher Zwei-Photonen-Mikroskopie

Polarization-Sensitive Two-Photon Microscopy for a Label-Free Amyloid Structural Characterization

Compared to its one-photon counterpart, two-photon excitation is beneficial for bioimaging experiments because of its lower phototoxicity, deeper tissue penetration, efficient operation in densely packed systems, and reduced angular photoselection of fluorophores. Thus, the introduction of polarization analysis in two-photon fluorescence microscopy (2PFM) provides a more precise determination of molecular organization in a sample compared to standard imaging methods based on linear optical processes. In this work, we focus on polarization-sensitive 2PFM (ps-2PFM) and its application in the determination of molecular ordering within complex bio-structures-amyloid spherulites. Neurodegenerative diseases such as Alzheimer's or Parkinson's are often diagnosed through the detection of amyloids-protein aggregates formed due to an impaired protein misfolding process. Exploring their structure leads to a better understanding of their creation pathway and consequently, to developing more sensitive diagnostic methods. This paper presents the ps-2PFM adapted for the determination of local fibril ordering inside the bovine insulin spherulites and spherical amyloidogenic protein aggregates. Moreover, we prove that the proposed technique can resolve the three-dimensional organization of fibrils inside the spherulite.

Autor im Fokus: Nicht-invasive Bildgebung komplexer Biostrukturen mittels polarisationssensitiver Zwei-Photonen-Mikroskopie 

This paper describes how polarization-sensitive two-photon microscopy could be applied to characterize the local organization within label-free amyloid superstructures-spherulites. It also describes how to prepare and measure the sample, assemble the required setup, and analyze the data to obtain information about the local organization of amyloid fibrils.

Polarisationsempfindliche Zwei-Photonen-Mikroskopie zur markierungsfreien Amyloid-Strukturcharakterisierung

Compared to its one-photon counterpart, two-photon excitation is beneficial for bioimaging experiments because of its lower phototoxicity, deeper tissue ...

Experimentelle Methoden für Spin - und Winkel-Resolved Photoemission Spectroscopy kombiniert mit Polarisation-Variable Laser

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