Name: advanced experimental methods for low-temperature magnetotransport measurement of novel materials
Uploaded: 2016-01-21T14:00:00.000+00:00
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Description: Watch this Scientific Journal Video about Advanced Experimental Methods for Low-temperature Magnetotransport Measurement of Novel Materials at JoVE.com

This work is supported by the National Institute of Standards and Technology of the United States Department of Commerce.

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The authors declare no competing financial interests. Commercial materials, instruments and equipment are identified in this paper to specify the experimental procedure as completely as possible. In no case does such identification imply a recommendation or endorsement by the National Institute of Standards.

適切な組成および構造を確保するために特徴の高品質バルクサンプルの取得後、サンプルは、基板から1cm×1cmの小片に試料の薄片を剥離することによって示される形状にパターニングします。これらは、バックゲートの適用を可能にすることによって、実験的パラメータ空間を増大させるようにSiO 2を300nm程度で覆われた高濃度にp型にドープされたシリコンからなる基板が好ましいで?...

高度なエレクトロニクス技術のための材料プラットフォームの追求は、ハイスループット材料の合成およびその後の特徴づけのための方法が求められています。この追求に関心の新規な材料は、分子線エピタキシー又はより複雑単結晶薄膜堆積技術よりも迅速な方法で直接反応合成1,2-、電気化学的成長3,4、及び他の方法5によって大量に生産することができます化学蒸着。バルク結晶サンプルの輸送特性を測定するための従来の方法は、約1ミリメートル×1ミリメートル×6mmの寸法を有する直方体状の断片を切断し、ワイヤは、ホールバー構成6のサンプルに導く取り付けることです。 特定の材料は、従来のバルクホールバー装置の製造方法は、検体搬送測定に測定可能な装置を製造するには不十分であることを特徴と課題を提起します。これは、することができます所望のサンプルの厚さはわずか数の単層への1程度であるため、または1つは、層状の二次元の積層体を測定することを目的とするため、生成した結晶は、さらに強力な光学顕微鏡下で、リード線を取り付けるには小さすぎる原因近またはサブナノメートルの厚さを有する材料。最初のカテゴリは、例えば、ナノワイヤのため、で構成され、モリブデン酸化物の特定の製剤は、7ブロンズ。第二のカテゴリーは、グラフェン8のような2次元の物質の単一の非常に-数層で構成され、のTMD（MoS 2、WTE 2、 など）、およびトポロジカル絶縁体（ の Bi 2 Seの3は 、BiがSbを1-X Teの3 xは 、 等 ）。第三のカテゴリーは、層転写、hBNの-グラフェンのhBN 9の最も顕著な三層スタックを介して、手動アセンブリによって二次元の材料の個々の層を積層することにより製造ヘテロ構造で構成されています。 小説の電子の探索的研究lectronic材料が困難な測定サンプル上のデバイスを製造するための適切な方法が求められています。多くの場合、直接反応または電気化学的成長により合成された新素材の最初のバッチは、ミクロンの大きさのオーダーの大きさで、非常に小さな単結晶が得られます。このようなサンプルは、歴史的に、新規な材料のハイスループット研究に障害物を提示する、より簡単に輸送装置の製造のためのより大きな結晶を得るためにサンプルの成長パラメータの改善が必要に金属接点を接続する非常に困難であることが判明しています。材料の迅速な特徴付けを可能にするために、非常に少量の試料のためのデバイスの製造の方法は、すぐに予備バッチが製造されているように、新規な材料の特徴付けを可能にするために考案されています。この方法のわずかな変化は、例えば、グラフェン、のhBNて、TMDSのような2次元材料から剥離した試料を使用するデバイス、ならびにそのようなMAの多層ヘテロ構造を製造に適用可能ですterials。装置は、市販の超伝導磁石、乾燥ヘリウムクローズサイクルクライオスタット磁気輸送システムに挿入するためのパッケージに付着し、ワイヤボンディングされています。輸送測定は、T 12まで0.300 Kまでの温度と磁場で撮影されています

<table><tbody><tr><td>Cryogenic Limited 12 T CFMS</td><td>Cryogen Limited</td><td>CFM-12T-H3- IVTI-25</td><td>Magnetotransport system customized with modulated field magnet (step 4)</td></tr><tr><td>7270 DSP Lock-in amplifier</td><td>Signal Recovery</td><td>7270</td><td>lock-in amplifier for source/drain and voltage measurements (step 4)</td></tr><tr><td>GS200 DC Voltage/Current Source</td><td>Yokogawa</td><td>GS200</td><td>Voltage source for gate voltage application (step 4)</td></tr><tr><td>2636B System Sourcemeter</td><td>Keithley</td><td>2636B</td><td>Sourcemeter for source/drain and voltage measurements</td></tr><tr><td>DWL 2000 Laser Pattern Generator</td><td>Heidelberg Instruments</td><td>DWL 2000</td><td>Generate chrome mask for lithography of substrate location/alignment feature pattern (step 1.3)</td></tr><tr><td>Suss MicroTec MA6/BA6 Contact Aligner</td><td>Suss</td><td>MA6</td><td>Used for the lithography of substrate location/alignment feature pattern (step 1.4.12)</td></tr><tr><td>JEOL Direct Write Electron Beam Lithography System</td><td>JEOL</td><td>JBX 6300-FS&amp;nbsp;</td><td>Perform high-resolution lithography of devices</td></tr><tr><td>Discovery 550 Sputtering System</td><td>Denton Vacuum</td><td>Discovery 550</td><td>Perform SiO&lt;sub&gt;2&lt;/sub&gt; sputtering (step 2.5)</td></tr><tr><td>Infinity 22 Electron Beam Evaporator</td><td>Denton Vacuum</td><td>Infinty 22</td><td>Perform Cr/Au deposition (steps 1.5 and 3.7)</td></tr><tr><td>Unaxis 790 Reactive Ion Etcher</td><td>Unaxis</td><td>Unaxis 790</td><td>Etch sample into Hall bar structure (step 3.4)</td></tr><tr><td>PMMA 495 A4</td><td>MicroChem</td><td>PMMA 495 A4</td><td>Polymer coating/electron beam mask for lithography (step 3.5.1)</td></tr><tr><td>PMMA 950 A4</td><td>MicroChem</td><td>PMMA 950 A4</td><td>Polymer coating/electron beam mask for sample dicing and lithography (steps 1.7.3, 3.3.1, and 3.5.2)</td></tr><tr><td>S1813 positive photoresist</td><td>MicroChem</td><td>S1813 G2</td><td>Positive photoresist (step 1.4.8)</td></tr><tr><td>LOR resist</td><td>MicroChem</td><td>LOR 3A</td><td>Lift off resist (step 1.4.3)</td></tr><tr><td>1:3 MIBK:IPA PMMA developer</td><td>MicroChem</td><td>1:3 MIBK:IPA</td><td>PMMA developer</td></tr><tr><td>MF-321 Developer</td><td>MicroChem</td><td>MF-321</td><td>Novolac positive photoresist-compatible developer solution (step 1.4.15)</td></tr><tr><td>Diglycidiyl ether-terminated polydimethylsiloxane</td><td>Sigma Aldrich</td><td>SA 480282</td><td>For layered material stacking (step 2.6.1)</td></tr><tr><td>Polypropylene carbonate</td><td>Sigma Aldrich</td><td>SA 389021</td><td>For layered material stacking (step 2.6.2)</td></tr></tbody></table>

advanced experimental methods for low-temperature magnetotransport measurement of novel materials

Novel electronic materials are often produced for the first time by synthesis processes that yield bulk crystals (in contrast to single crystal thin film synthesis) for the purpose of exploratory materials research. Certain materials pose a challenge wherein the traditional bulk Hall bar device fabrication method is insufficient to produce a measureable device for sample transport measurement, principally because the single crystal size is too small to attach wire leads to the sample in a Hall bar configuration. This can be, for example, because the first batch of a new material synthesized yields very small single crystals or because flakes of samples of one to very few monolayers are desired. In order to enable rapid characterization of materials that may be carried out in parallel with improvements to their growth methodology, a method of device fabrication for very small samples has been devised to permit the characterization of novel materials as soon as a preliminary batch has been produced. A slight variation of this methodology is applicable to producing devices using exfoliated samples of two-dimensional materials such as graphene, hexagonal boron nitride (hBN), and transition metal dichalcogenides (TMDs), as well as multilayer heterostructures of such materials. Here we present detailed protocols for the experimental device fabrication of fragments and flakes of novel materials with micron-sized dimensions onto substrate and subsequent measurement in a commercial superconducting magnet, dry helium close-cycle cryostat magnetotransport system at temperatures down to 0.300 K and magnetic fields up to 12 T.

図3は、低温の磁気輸送実験の目的のための典型的なパターン化されたホールバー装置を示しています。上図中の光学像が正常に製作グラフェン/ hBNのホールバーを示しています。下側の画像はランダウレベル（LLS）から生じるランダウアー-Büttiker端状態、量子化されたホール抵抗の値を計算するために使用することができるトランスポート機構として議...

Watch this Scientific Journal Video about Advanced Experimental Methods for Low-temperature Magnetotransport Measurement of Novel Materials at JoVE.com

Advanced Experimental Methods for Low-temperature Magnetotransport Measurement of Novel Materials

新規材料の低温磁気伝導測定のための高度な実験方法

We describe the methodology of mechanical exfoliation and deposition of flakes of novel materials with micron-sized dimensions onto substrate, fabrication of experimental device structures for transport experimentation, and the magnetotransport measurement in a dry helium close-cycle cryostat at temperatures down to 0.300 K and magnetic fields up to 12 T.

Novel electronic materials are often produced for the first time by synthesis processes that yield bulk crystals (in contrast to single crystal thin film ...

advanced-experimental-methods-for-low-temperature-magnetotransport

Universidad San Sebastian

Research

JoVE Journal

Engineering

10.5K ビュー.  National Institute of Standards and Technology. We describe the methodology of mechanical exfoliation and deposition of flakes of novel materials with micron-sized dimensions onto substrate, fabrication of experimental device structures for transport experimentation, and the magnetotransport measurement in a dry helium close-cycle cryostat at temperatures down to 0.300 K and magnetic fields up to 12 T.

ビデオ: Advanced Experimental Methods for Low-temperature Magnetotransport Measurement of Novel Materials

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.

超低温での角度分解光電子分光

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

工学

Sputter Growth and Characterization of Metamagnetic B2-ordered FeRh Epilayers

Chemically ordered alloys are useful in a variety of magnetic nanotechnologies. They are most conveniently prepared at an industrial scale using sputtering techniques. Here we describe a method for preparing epitaxial thin films of B2-ordered FeRh by sputter deposition onto single crystal MgO substrates. Deposition at a slow rate onto a heated substrate allows time for the adatoms to both settle into a lattice with a well-defined epitaxial relationship with the substrate and also to find their proper places in the Fe and Rh sublattices of the B2 structure. The structure is conveniently characterized with X-ray reflectometry and diffraction and can be visualised directly using transmission electron micrograph cross-sections. B2-ordered FeRh exhibits an unusual metamagnetic phase transition: the ground state is antiferromagnetic but the alloy transforms into a ferromagnet on heating with a typical transition temperature of about 380 K. This is accompanied by a 1% volume expansion of the unit cell: isotropic in bulk, but laterally clamped in an epilayer. The presence of the antiferromagnetic ground state and the associated first order phase transition is very sensitive to the correct equiatomic stoichiometry and proper B2 ordering, and so is a convenient means to demonstrate the quality of the layers that can be deposited with this approach. We also give some examples of the various techniques by which the change in phase can be detected.

A method to prepare epitaxial layers of ordered alloys by sputtering is described. The B2-ordered FeRh compound is used as an example, as it displays a metamagnetic transition that depends sensitively on the degree of chemical order and the exact composition of the alloy.

メタ磁性B2-命じFeRhエピ層のスパッタ成長と評価

Chemically ordered alloys are useful in a variety of magnetic nanotechnologies. They are most conveniently prepared at an industrial scale using ...

Writing and Low-Temperature Characterization of Oxide Nanostructures

Oxide nanoelectronics is a rapidly growing field which seeks to develop novel materials with multifunctional behavior at nanoscale dimensions. Oxide interfaces exhibit a wide range of properties that can be controlled include conduction, piezoelectric behavior, ferromagnetism, superconductivity and nonlinear optical properties. Recently, methods for controlling these properties at extreme nanoscale dimensions have been discovered and developed. Here are described explicit step-by-step procedures for creating LaAlO3/SrTiO3 nanostructures using a reversible conductive atomic force microscopy technique. The processing steps for creating electrical contacts to the LaAlO3/SrTiO3 interface are first described. Conductive nanostructures are created by applying voltages to a conductive atomic force microscope tip and locally switching the LaAlO3/SrTiO3 interface to a conductive state. A versatile nanolithography toolkit has been developed expressly for the purpose of controlling the atomic force microscope (AFM) tip path and voltage. Then, these nanostructures are placed in a cryostat and transport measurements are performed. The procedures described here should be useful to others wishing to conduct research in oxide nanoelectronics.

Oxide nanostructures provide new opportunities for science and technology. The interfacial conductivity between LaAlO3 and SrTiO3 can be controlled with near-atomic precision using a conductive atomic force microscopy technique. The protocol for creating and measuring conductive nanostructures at LaAlO3/SrTiO3 interfaces is demonstrated.

書き込みおよび酸化物ナノ構造の低温特性評価

Oxide nanoelectronics is a rapidly growing field which seeks to develop novel materials with multifunctional behavior at nanoscale dimensions.  Oxide ...

Chemical Vapor Deposition of an Organic Magnet, Vanadium Tetracyanoethylene

Recent progress in the field of organic materials has yielded devices such as organic light emitting diodes (OLEDs) which have advantages not found in traditional materials, including low cost and mechanical flexibility. In a similar vein, it would be advantageous to expand the use of organics into high frequency electronics and spin-based electronics. This work presents a synthetic process for the growth of thin films of the room temperature organic ferrimagnet, vanadium tetracyanoethylene (V[TCNE]x, x~2) by low temperature chemical vapor deposition (CVD). The thin film is grown at &#60;60 &#176;C, and can accommodate a wide variety of substrates including, but not limited to, silicon, glass, Teflon and flexible substrates. The conformal deposition is conducive to pre-patterned and three-dimensional structures as well. Additionally this technique can yield films with thicknesses ranging from 30 nm to several microns. Recent progress in optimization of film growth creates a film whose qualities, such as higher Curie temperature (600 K), improved magnetic homogeneity, and narrow ferromagnetic resonance line-width (1.5 G) show promise for a variety of applications in spintronics and microwave electronics.

We present the synthesis of the organic-based ferrimagnet vanadium tetracyanoethylene (V[TCNE]x, x~2) via low temperature chemical vapor deposition (CVD). This optimized recipe yields an increase in Curie temperature from 400 K to over 600 K and a dramatic improvement in magnetic resonance properties.

有機マグネットの化学気相堆積、バナジウムテトラ

Recent progress in the field of organic materials has yielded devices such as organic light emitting diodes (OLEDs) which have advantages not found in ...

化学

All-electronic Nanosecond-resolved Scanning Tunneling Microscopy: Facilitating the Investigation of Single Dopant Charge Dynamics

The miniaturization of semiconductor devices to scales where small numbers of dopants can control device properties requires the development of new techniques capable of characterizing their dynamics. Investigating single dopants requires sub-nanometer spatial resolution, which motivates the use of scanning tunneling microscopy (STM). However, conventional STM is limited to millisecond temporal resolution. Several methods have been developed to overcome this shortcoming, including all-electronic time-resolved STM, which is used in this study to examine dopant dynamics in silicon with nanosecond resolution. The methods presented here are widely accessible and allow for local measurement of a wide variety of dynamics at the atomic scale. A novel time-resolved scanning tunneling spectroscopy technique is presented and used to efficiently search for dynamics.

We demonstrate an all-electronic method to observe nanosecond-resolved charge dynamics of dopant atoms in silicon with a scanning tunneling microscope.

すべて電子ナノ秒分解走査型トンネル顕微鏡: 単一ドーパントの電荷ダイナミクスの調査を促進します。

The miniaturization of semiconductor devices to scales where small numbers of dopants can control device properties requires the development of new ...

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

We demonstrate the use of two nuclear-based analytical methods that can follow the modifications of microstructural arrangement of iron-based metallic glasses (MGs). Despite their amorphous nature, the identification of hyperfine interactions unveils faint structural modifications. For this purpose, we have employed two techniques that utilize nuclear resonance among nuclear levels of a stable 57Fe isotope, namely M&#246;ssbauer spectrometry and nuclear forward scattering (NFS) of synchrotron radiation. The effects of heat treatment upon (Fe2.85Co1)77Mo8Cu1B14 MG are discussed using the results of ex situ and in situ experiments, respectively. As both methods are sensitive to hyperfine interactions, information on structural arrangement as well as on magnetic microstructure is readily available. M&#246;ssbauer spectrometry performed ex situ describes how the structural arrangement and magnetic microstructure appears at room temperature after the annealing under certain conditions (temperature, time), and thus this technique inspects steady states. On the other hand, NFS data are recorded in situ during dynamically changing temperature and NFS examines transient states. The use of both techniques provides complementary information. In general, they can be applied to any suitable system in which it is important to know its steady state but also transient states.

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

Here, we present a protocol to describe ex situ and in situ investigations of structural transformations in metallic glasses. We employed nuclear-based analytical methods which inspect hyperfine interactions. We demonstrate the applicability of M&#246;ssbauer spectrometry and nuclear forward scattering of synchrotron radiation during temperature-driven experiments.

Ex その場その場で調査構造変換の方法: 金属ガラスの結晶化の事例

We demonstrate the use of two nuclear-based analytical methods that can follow the modifications of microstructural arrangement of iron-based metallic ...

Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope

The quest to understand correlated electronic systems has pushed the frontiers of experimental measurements toward the development of new experimental techniques and methodologies. Here we use a novel home-built uniaxial-strain device integrated into our variable temperature scanning tunneling microscope that enables us to controllably manipulate in-plane uniaxial strain in samples and probe their electronic response at the atomic scale. Using scanning tunneling microscopy (STM) with spin-polarization techniques, we visualize antiferromagnetic (AFM) domains and their atomic structure in Fe1+yTe samples, the parent compound of iron-based superconductors, and demonstrate how these domains respond to applied uniaxial strain. We observe the bidirectional AFM domains in the unstrained sample, with an average domain size of ~50-150 nm, to transition into a single unidirectional domain under applied uniaxial strain. The findings presented here open a new direction to utilize a valuable tuning parameter in STM, as well as other spectroscopic techniques, both for tuning the electronic properties as for inducing symmetry breaking in quantum material systems.

Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope

Using uniaxial strain combined with spin-polarized scanning tunneling microscopy, we visualize and manipulate the antiferromagnetic domain structure of Fe1+yTe, the parent compound of iron-based superconductors.

一軸歪 Fe1 +Yスピン偏極走査トンネル顕微鏡を使用して Te の反強磁性ドメイン操作を可視化

The quest to understand correlated electronic systems has pushed the frontiers of experimental measurements toward the development of new experimental ...

Magnetic Field Mapping using Off-Axis Electron Holography in the Transmission Electron Microscope

Off-axis electron holography is a powerful technique that involves the formation of an interference pattern in a transmission electron microscope (TEM) by overlapping two parts of an electron wave, one of which has passed through a region of interest on a specimen and the other is a reference wave. The resulting off-axis electron hologram can be analyzed digitally to recover the phase difference between the two parts of the electron wave, which can then be interpreted to provide quantitative information about local variations in electrostatic potential and magnetic induction within and around the specimen. Off-axis electron holograms can be recorded while a specimen is subjected to external stimuli such as elevated or reduced temperature, voltage, or light. The protocol that is presented here describes the practical steps that are required to record, analyze, and interpret off-axis electron holograms, with a primary focus on the measurement of magnetic fields within and around nanoscale materials and devices. Presented here are the steps involved in the recording, analysis, and processing of off-axis electron holograms, as well as the reconstruction and interpretation of phase images and visualization of the results. Also discussed are the need for optimization of the specimen geometry, the electron optical configuration of the microscope, and the electron hologram acquisition parameters, as well as the need for the use of information from multiple holograms to extract the desired magnetic contributions from the recorded signal. The steps are illustrated through a study of specimens of B20-type FeGe, which contain magnetic skyrmions and were prepared with focused ion beams (FIBs). Prospects for the future development of the technique are discussed.

Guidelines are presented for recording and interpreting off-axis electron holograms to provide quantitative images of magnetic fields in nanoscale materials and devices in the transmission electron microscope.

Off-axis electron holography is a powerful technique that involves the formation of an interference pattern in a transmission electron microscope (TEM) by ...

Optimizing Magnetic Force Microscopy Resolution and Sensitivity to Visualize Nanoscale Magnetic Domains

Magnetic force microscopy (MFM) enables mapping local magnetic fields across a sample surface with nanoscale resolution. To perform MFM, an atomic force microscopy (AFM) probe whose tip has been magnetized vertically (i.e., perpendicular to the probe cantilever) is oscillated at a fixed height above the sample surface. The resultant shifts in the oscillation phase or frequency, which are proportional to the magnitude and sign of the vertical magnetic force gradient at each pixel location, are then tracked and mapped. Although the spatial resolution and sensitivity of the technique increases with decreasing lift height above the surface, this seemingly straightforward path to improved MFM images is complicated by considerations such as minimizing topographical artifacts due to shorter range van der Waals forces, increasing the oscillation amplitude to further improve sensitivity, and the presence of surface contaminants (in particular water due to humidity under ambient conditions). In addition, due to the orientation of the probe's magnetic dipole moment, MFM is intrinsically more sensitive to samples with an out-of-plane magnetization vector. Here, high-resolution topographical and magnetic phase images of single and bicomponent nanomagnet artificial spin-ice (ASI) arrays obtained in an inert (argon) atmosphere glovebox with &lt;0.1 ppm O2 and H2O are reported. Optimization of lift height and drive amplitude for high resolution and sensitivity while simultaneously avoiding the introduction of topographical artifacts is discussed, and detection of the stray magnetic fields emanating from either end of the nanoscale bar magnets (~250 nm long and &lt;100 nm wide) aligned in the plane of the ASI sample surface is shown. Likewise, using the example of a Ni-Mn-Ga magnetic shape memory alloy (MSMA), MFM is demonstrated in an inert atmosphere with magnetic phase sensitivity capable of resolving a series of adjacent magnetic domains each ~200 nm wide.

Magnetic force microscopy (MFM) employs a vertically magnetized atomic force microscopy probe to measure sample topography and local magnetic field strength with nanoscale resolution. Optimizing MFM spatial resolution and sensitivity requires balancing decreasing lift height against increasing drive (oscillation) amplitude, and benefits from operating in an inert atmosphere glovebox.

ナノスケールの磁区を可視化するための磁気力顕微鏡の分解能と感度の最適化

Magnetic force microscopy (MFM) enables mapping local magnetic fields across a sample surface with nanoscale resolution. To perform MFM, an atomic force ...

酸化還元活性MOFの磁気特性評価:固体電気化学

Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks

Electrochemical energy storage has been a widely discussed application of redox-active metal-organic frameworks (MOFs) in the past 5 years. Although MOFs show outstanding performance in terms of gravimetric or areal capacitance and cyclic stability, unfortunately their electrochemical mechanisms are not well understood in most cases. Traditional spectroscopic techniques, such as X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS), have only provided vague and qualitative information about valence changes of certain elements, and the mechanisms proposed based on such information are often highly disputable. In this article, we report a series of standardized methods, including the fabrication of solid-state electrochemical cells, electrochemistry measurements, the disassembly of cells, the collection of MOF electrochemical intermediates, and physical measurements of the intermediates under the protection of inert gases. By using these methods for quantitatively clarifying the electronic and spin state evolution within a single electrochemical step of redox-active MOFs, one can provide clear insight into the nature of electrochemical energy storage mechanisms not only for MOFs, but also for all other materials with strongly correlated electronic structures.

著者スポットライト:酸化還元活性金属有機フレームワークの固体電気化学における中間体の磁気測定特性評価  

Ex situ magnetic surveys can directly provide bulk and local information on a magnetic electrode to reveal its charge storage mechanism step by step. Herein, electron spin resonance (ESR) and magnetic susceptibility are demonstrated to monitor the evaluation of paramagnetic species and their concentration in a redox-active metal-organic framework (MOF).

酸化還元活性金属-有機骨格の固体電気化学における中間体の磁気特性評価

Electrochemical energy storage has been a widely discussed application of redox-active metal-organic frameworks (MOFs) in the past 5 years. Although MOFs ...