Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

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Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

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Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

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Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

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Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

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Publishing type：Research paper (scientific journal)   Publisher：American Physical Society (APS)  

DOI： 10.1103/physrevb.108.064429

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Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevB.108.064429/fulltext

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

Amorphous semiconductors are widely applied to electronic and energy-conversion devices owing to their high performance and simple fabrication processes. The topological concept of the Berry curvature is generally ill-defined in amorphous solids, due to the absence of long-range crystalline order. Here, we demonstrate that the Berry curvature in the short-range crystalline order of kagome-lattice fragments effectively contributes to the anomalous electrical and magneto-thermoelectric properties in Fe–Sn amorphous films. The Fe–Sn films on glass substrates exhibit large anomalous Hall and Nernst effects comparable to those of the single crystals of topological semimetals Fe₃Sn₂ and Fe₃Sn. With modelling, we reveal that the Berry curvature contribution in the amorphous state likely originates from randomly distributed kagome-lattice fragments. This microscopic interpretation sheds light on the topology of amorphous materials, which may lead to the realization of functional topological amorphous electronic devices.

DOI： 10.1038/s41467-023-39112-1

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Other Link： https://www.nature.com/articles/s41467-023-39112-1

Publishing type：Research paper (scientific journal)   Publisher：American Physical Society (APS)  

DOI： 10.1103/physrevmaterials.7.l051801

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Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevMaterials.7.L051801/fulltext

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.11470/jsaprev.230414

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Publishing type：Research paper (scientific journal)   Publisher：American Physical Society (APS)  

DOI： 10.1103/physrevresearch.5.013222

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Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevResearch.5.013222/fulltext

Authorship：Lead author,　Corresponding author   Language：English  

DOI： 10.1063/5.0134291

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Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.tsf.2023.139740

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Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1038/s42005-022-01106-8

Scopus

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Other Link： https://www.nature.com/articles/s42005-022-01106-8

Publishing type：Research paper (scientific journal)   Publisher：American Physical Society (APS)  

DOI： 10.1103/physrevmaterials.6.114203

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Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevMaterials.6.114203/fulltext

Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1002/adma.202206801

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Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

Abstract

Unidirectional magnetoresistance (UMR) is an attractive magnetic-field sensing technique as it enables detecting the in-plane direction of the external magnetic field with a single element. However, the UMR amplitude is typically several orders of magnitude smaller than those of other directional magnetoresistances exhibited in ferromagnetic thin films, hindering sensing applications using the UMR. For a directional magnetic sensor using the UMR, the in-depth understanding of mechanisms of the UMR and its enhancement are highly desirable. In this study, the structural dependence of the UMR in Fe-Sn heterostructure devices is investigated. We find a weak dependence of the UMR on interface configuration in the oxide cap/Fe-Sn heterostructures on various oxide substrates. In contrast, the normalized UMR amplitude is enhanced by a factor of 27 with increasing the Fe-Sn layer thickness from 4.0 to 100 nm. These results suggest that the magnetothermal effect dominates the large UMR in the Fe-Sn heterostructure devices.

DOI： 10.35848/1347-4065/ac7bc8

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Other Link： https://iopscience.iop.org/article/10.35848/1347-4065/ac7bc8/pdf

Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

We report the effect of annealing on the crystalline ordering and physical properties in thin films of a nodal line semimetal candidate L2₁-type Co₂FeSn. The Co–Fe–Sn films with a composition of Co:Fe:Sn ∼ 2:1:1 were deposited on MgO(001) substrates at a substrate temperature of 150 °C by radio-frequency magnetron sputtering. The as-deposited film showed x-ray diffraction patterns corresponding to the B2 ordering. Annealing at 600 and 700 °C after the deposition resulted in the appearance of the (111) diffraction peak, which is characteristic of the L2₁ ordering. Although anomalous Hall conductivity and transverse thermoelectric conductivity decreased from those of the as-deposited film with the annealing-induced L2₁ ordering, the low anomalous Hall conductivity of the 700 °C-annealed film was consistent with the theoretically estimated low value. These results show the significant influence of crystalline ordering on the electrical and thermoelectric transport properties. The annealing process is beneficial for studying the exotic physics arising from topological band features in the L2₁-ordered Co₂FeSn thin films.

DOI： 10.1063/5.0093195

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Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

DOI： 10.1063/5.0078021

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Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

Abstract

A ferromagnetic nanocrystalline Fe-Sn is an excellent platform for magnetic-field sensor based on anomalous Hall effect (AHE) owing to simple fabrication and superior thermal stability. For improvement of the magnetic-field sensitivity, doping impurity and increasing injection current are effective approaches. However, in the light of magnetic-field detectivity, the large current may increase the voltage noise. In this study, a maximum allowable current of was improved by employing the overlayer electrode configuration on a Ta-doped Fe-Sn AHE sensor. In noise measurements, the 1/f noise becomes significant with increasing the current at low frequency, resulting in saturation of the detectivity to 240 nTHz-1/2 at 120 Hz. At high frequency, the detectivity reaches 48 nTHz-1/2 at 3.1 mA showing ten times improvement of the detectivity compared with the non-doped Fe-Sn AHE sensor. Material design and device structure optimization will accelerate further improvement of the sensing properties of the Fe-Sn-based AHE sensor.

DOI： 10.35848/1347-4065/ac465a

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Other Link： https://iopscience.iop.org/article/10.35848/1347-4065/ac465a/pdf

Publishing type：Research paper (scientific journal)   Publisher：American Association for the Advancement of Science (AAAS)  

Ferromagnetic-metal surface state derived from topological polarization and its spin-orbitronics functionalities in FeSi.

DOI： 10.1126/sciadv.abj0498

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

Abstract

Non-coplanar spin textures with finite scalar spin chirality can be artificially induced at surfaces and interfaces through the interfacial Dzyaloshinskii-Moriya interaction. However, stabilizing a proper magnetic skyrmion crystal via this route remains elusive. Here, using an epitaxial bilayer of platinum and geometrically frustrated kagome-lattice ferromagnet Fe₃Sn, we show the possible formation of a two-dimensional skyrmion crystal under well-regulated Fe₃Sn thickness conditions. Magnetization measurements reveal that the magnetic anisotropy is systematically varied from an inherent in-plane type to a perpendicular type with the thickness reduction. Below approximately 0.5 nm, we clearly detect a topological Hall effect that provides evidence for finite scalar spin chirality. Our topological Hall effect analysis, combined with theoretical simulations, not only establishes its interfacial Dzyaloshinskii-Moriya interaction origin, but also indicates the emergence of a stable skyrmion crystal phase, demonstrating the potential of kagome-lattice ferromagnets in spin chirality engineering using thin-film nanostructures.

DOI： 10.1038/s43246-021-00218-y

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Other Link： https://www.nature.com/articles/s43246-021-00218-y

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1038/s43246-021-00206-2

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Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

DOI： 10.35848/1882-0786/ac114e

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Other Link： https://iopscience.iop.org/article/10.35848/1882-0786/ac114e/pdf

Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

DOI： 10.1541/ieejeiss.141.767

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

<title>Abstract</title>Two-dimensional (2D) surface of the topological materials is an attractive channel for the electrical conduction reflecting the linearly-dispersive electronic bands. Thickness-dependent sheet conductance measurement is a reliable method to evaluate the 2D and three-dimensional (3D) electrical conducting channel separately but has rarely been applied for Weyl semimetals. By applying this method to thin films of a Weyl semimetal Co₃Sn₂S₂, here we show that the 2D conducting channel clearly emerges under the ferromagnetic phase, indicating a formation of the Fermi arcs projected from Weyl nodes. Comparison between 3D conductivity and 2D conductance provides the effective thickness of the surface conducting region being estimated to be approximately 20 nm, which would reflect the Weyl feature of electronic bands of the Co₃Sn₂S₂. The emergent surface conduction will provide a pathway to activate quantum and spintronic transport features stemming from a Weyl node in thin-film-based devices.

DOI： 10.1038/s42005-021-00627-y

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Other Link： http://www.nature.com/articles/s42005-021-00627-y

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1103/physrevb.103.205112

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Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevB.103.205112/fulltext

Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1038/s43246-021-00122-5

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1103/physrevmaterials.5.024403

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Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevMaterials.5.024403/fulltext

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1038/s41467-020-18470-0

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Other Link： http://www.nature.com/articles/s41467-020-18470-0

Authorship：Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

<title>Abstract</title>In quantum spin liquid research, thin films are an attractive arena that enables the control of magnetic interactions via epitaxial strain and two-dimensionality, which are absent in bulk crystals. Here, as a promising candidate for the development of quantum spin liquids in thin films, we propose a robust ilmenite-type oxide with a honeycomb lattice of edge-sharing IrO₆ octahedra artificially stabilised by superlattice formation using the ilmenite-type antiferromagnetic oxide MnTiO₃. Stabilised sub-unit-cell-thick Mn–Ir–O layers are isostructural to MnTiO₃ and have an atomic arrangement corresponding to ilmenite-type MnIrO₃. By performing spin Hall magnetoresistance measurements, we observe that antiferromagnetic ordering in the ilmenite Mn sublattice is suppressed by modified magnetic interactions in the MnO₆ planes via the IrO₆ planes. These findings contribute to the development of two-dimensional Kitaev candidate materials, accelerating the discovery of exotic physics and applications specific to quantum spin liquids.

DOI： 10.1038/s43246-020-00059-1

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Other Link： http://www.nature.com/articles/s43246-020-00059-1

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACS Publications  

DOI： 10.1021/acs.chemmater.0c01497

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1103/physrevmaterials.4.044202

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Other Link： https://link.aps.org/article/10.1103/PhysRevMaterials.4.044202

Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Physical Society (APS)  

DOI： 10.1103/physrevresearch.2.013282

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Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevResearch.2.013282/fulltext

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1103/PhysRevB.101.125125

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1063/1.5142193

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1063/1.5126499

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.7567/1882-0786/ab506a

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.7567/1347-4065/ab12ff

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1063/1.5090407

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1038/s41598-019-39817-8

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1063/1.5079719

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1063/1.5054289

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.7567/1882-0786/aaf285

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1063/1.5064736

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1103/PhysRevB.98.125415

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1063/1.5034403

Scopus

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：American Institute of Physics Inc.  

DOI： 10.1063/1.5027579

Scopus

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1103/PhysRevMaterials.2.031801

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1088/1361-648X/aaa724

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Institute of Physics  

We report the synthesis of tetragonal FeS<inf>x</inf>Se<inf>1−</inf><inf>x</inf>films (x ≤ 0.78) by pulsed-laser deposition. To fabricate tetragonal alloy films with tetragonal FeSe and hexagonal FeS targets, we adopted an alternate deposition technique with an FeSe buffer layer on MgO(001). The overall film composition is controlled by the thickness ratio of FeS/FeSe layers. The out-of-plane lattice parameter of the films follows Vegard’s law, demonstrating homogeneous alloying by interdiffusion. The sulfur solid solubility reaches x = 0.78 in the FeS<inf>x</inf>Se<inf>1−</inf><inf>x</inf>films, which is by far higher than x ∼ 0.40 in bulk governed by the tetragonal phase instability.

DOI： 10.7567/JJAP.56.100308.

CiNii Article

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1063/1.4983611

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1063/1.4961637

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1063/1.4941233

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1063/1.4940387

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.7567/APEX.8.073201

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1021/acs.nanolett.5b00264

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Surface Science Society of Japan  

DOI： 10.1380/ejssnt.2015.279

Scopus

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1063/1.4890109

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1038/srep05818

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1002/admi.201300108

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.ssc.2014.02.014

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.7567/JJAP.53.05FA10

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.7567/APEX.7.045201

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1038/ncomms3893

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1063/1.4829469

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.7567/JJAP.52.068002

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1088/0022-3727/46/15/155108

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.7567/APEX.6.035201

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.7567/JJAP.52.015001

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1088/0957-4484/23/48/485308

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1063/1.4773371

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1063/1.4739719

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1143/JJAP.49.060215

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1103/PhysRevB.81.113107

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1103/PhysRevLett.104.106401

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1143/APEX.2.081401

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1063/1.3175720

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1143/JJAP.47.6266

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Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1143/JJAP.42.L1408

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

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Presentation type：Oral presentation (invited, special)  

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Language：Japanese   Presentation type：Oral presentation (invited, special)  

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Language：English   Presentation type：Oral presentation (invited, special)  

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Language：Japanese   Presentation type：Oral presentation (invited, special)  

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Language：Japanese   Presentation type：Oral presentation (invited, special)  

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Language：Japanese   Presentation type：Oral presentation (invited, special)  

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Language：Japanese   Presentation type：Oral presentation (invited, special)  

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Language：Japanese   Presentation type：Oral presentation (invited, special)  

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Language：English   Presentation type：Oral presentation (invited, special)  

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Language：English   Presentation type：Oral presentation (invited, special)  

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Language：English   Presentation type：Oral presentation (invited, special)  

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Language：Japanese   Presentation type：Oral presentation (invited, special)  

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Language：Japanese   Presentation type：Oral presentation (invited, special)  

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Language：Japanese   Presentation type：Oral presentation (invited, special)  

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Applicant：東北大学、三菱ケミカル株式会社

Application no：特願2023-047069  Date applied：23 3 2023

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Applicant：東北大学

Application no：特願PCT/JP2022/6778  Date applied：18 2 2022

Patent/Registration no：特許第7244157  Date registered：13 3 2023 

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Applicant：独立行政法人理化学研究所

Application no：特願2010-191414  Date applied：27 8 2010

Announcement no：特開2012-049403  Date announced：8 3 2012

Patent/Registration no：特許第5590488号  Date issued：8 8 2014

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Applicant：株式会社東京大学TLO、エヌイーシーショットコンポーネンツ株式会社

Application no：特願2004-079818  Date applied：19 3 2004

Announcement no：特開2005-268578  Date announced：29 9 2005

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