研究者詳細 - 矢野　力三

論文 - 矢野　力三

分割表示 >> ／全件表示 18 件中 1 - 18 件目

Evidence of unconventional superconductivity on the surface of the nodal semimetal CaAg1-xPdxP 査読有り国際誌

Yano, R; Nagasaka, S; Matsubara, N; Saigusa, K; Tanda, T; Ito, S; Yamakage, A; Okamoto, Y; Takenaka, K; Kashiwaya, S

NATURE COMMUNICATIONS 14 巻 ( 1 ) 頁： 6817 2023年10月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nature Communications

Surface states of topological materials provide extreme electronic states for unconventional superconducting states. CaAg1−xPd xP is an ideal candidate for a nodal-line Dirac semimetal with drumhead surface states and no additional bulk bands. Here, we report that CaAg1−xPd xP has surface states that exhibit unconventional superconductivity (SC) around 1.5 K. Extremely sharp magnetoresistance, tuned by surface-sensitive gating, determines the surface origin of the ultrahigh-mobility “electrons.” The Pd-doping elevates the Fermi level towards the surface states, and as a result, the critical temperature (T c) is increased up to 1.7 K from 1.2 K for undoped CaAgP. Furthermore, a soft point-contact study at the surface of Pd-doped CaAgP proved the emergence of unconventional SC on the surface. We observed the bell-shaped conductance spectra, a hallmark of the unconventional SC. Ultrahigh mobility carriers derived from the surface flat bands generate a new class of unconventional SC.

DOI： 10.1038/s41467-023-42535-5

Web of Science

Scopus

PubMed

Magnetic Gap of Fe-Doped BiSbTe2Se Bulk Single Crystals Detected by Tunneling Spectroscopy and Gate-Controlled Transports 査読有り国際共著国際誌

Yano, R; Kudriashov, A; Hirose, HT; Tsuda, T; Kashiwaya, H; Sasagawa, T; Golubov, AA; Stolyarov, VS; Kashiwaya, S

JOURNAL OF PHYSICAL CHEMISTRY LETTERS 12 巻 ( 17 ) 頁： 4180 - 4186 2021年5月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Physical Chemistry Letters

Topological insulators with broken time-reversal symmetry and the Fermi level within the magnetic gap at the Dirac cone provides exotic topological magneto-electronic phenomena. Here, we introduce an improved magnetically doped topological insulator, Fe-doped BiSbTe2Se (Fe-BSTS) bulk single crystal, with an ideal Fermi level. Scanning tunneling microscopy and spectroscopy (STM/STS) measurements revealed that the surface state possesses a Dirac cone with the Dirac point just below the Fermi level by 12 meV. The normalized dI/dV spectra suggest a gap opening with Δmag ~55 meV, resulting in the Fermi level within the opened gap. Ionic-liquid gated-transport measurements also support the Dirac point just below the Fermi level and the presence of the magnetic gap. The chemical potential of the surface state can be fully tuned by ionic-liquid gating, and thus the Fe-doped BSTS provides an ideal platform to investigate exotic quantum topological phenomena.

DOI： 10.1021/acs.jpclett.1c00869

Web of Science

Scopus

PubMed

Unusual Superconducting Proximity Effect in Magnetically Doped Topological Josephson Junctions 査読有り国際誌

Yano, R; Koyanagi, M; Kashiwaya, H; Tsumura, K; Hirose, HT; Sasagawa, T; Asano, Y; Kashiwaya, S

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 89 巻 ( 3 ) 頁： 034702 - 034702 2020年3月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of the Physical Society of Japan

The transport properties of a topological Josephson junction fabricated from a magnetically doped topological insulator (TI) were investigated. The conductance spectra of the Nb=Fe-Bi2Te2Se=Nb junction below 1 K showed an unusual trident-shaped zero-bias conductance peak with a tiny peak width of ∼6 µV. The central peak of the trident peak presents the dc-Josephson current, and the side peaks may reflect an induced unconventional Cooper pairing. Additionally, the critical currents followed inverse to temperature, which may also reflect the presence of an unconventional proximity effect. Furthermore, microwave irradiation drived a drastic change in the conductance spectra from the peak structure into oscillatory ones, a hallmark of the ac-Josephson supercurrent. The current-phase relation of the ac-Josephson effect under high power radiofrequency-irradiation was found to be 4π-periodic. The results suggest that the junction based on magnetically doped 3D TIs may realize an unconventional Cooper pairing, thus enabling access to the basic physics of Majorana bound states and unconventional superconductivity.

DOI： 10.7566/JPSJ.89.034702

Web of Science

Scopus

Theory of Josephson current on a lattice model of grain boundary in d-wave superconductors 査読有り国際誌

Sakamori, T; Kashiwaya, S; Yano, R; Tanaka, Y; Hatano, T; Yada, K

SUPERCONDUCTOR SCIENCE & TECHNOLOGY 36 巻 ( 8 ) 2023年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Superconductor Science and Technology

Identifying the origins of suppression of the critical current at grain boundaries of high-critical-temperature superconductors, such as cuprates and iron-based superconductors, is a crucial issue to be solved for future applications with polycrystalline materials. Although the dominant factor of current suppression might arise during material fabrication and/or processing, investigating it due to an internal phase change of the pair potential is an important issue in understanding the threshold of the critical current. In this paper, we study the Josephson current on a symmetric [001]-tilt grain boundary (GB) of a d-wave superconductor on a lattice model. In addition to the suppression of the maximum Josephson current associated with the internal phase change of the d-wave pair potential which has been predicted in continuum models, we find a unique phase interference effect due to folding of the Fermi surface in the lattice model. In particular, the resultant maximum Josephson current at low-tilting-angle regions tends to be suppressed more than that in preexisting theories. Because similar suppressions of the critical current at GBs have been reported in several experimental works, the present model can serve as a guide to clarify the complicated transport mechanism in GBs.

DOI： 10.1088/1361-6668/acdeaf

Web of Science

Scopus

Evaluation of Magnetic Field Induced by Time-Reversal Symmetry Broken Superconductors 査読有り

Mitsuhiro Teshigawara, Yasunori Mawatari, Hirotake Yamamori, Rikizo Yano, and Satoshi Kashiwaya

Proceedings of the 29th International Conference on Low Temperature Physics (LT29) 38 巻頁： 011069 2023年5月

Transport Properties of Magnetically doped Topological Insulator Fe-BiSbTe₂Se 査読有り

Tsuyoshi Tanda, Rikizo Yano, Hishiro T. Hirose, Takao Sasagawa, and Satoshi Kashiwaya

Proceedings of the 29th International Conference on Low Temperature Physics (LT29) 38 巻頁： 011180 2023年5月

Andreev Bound States and Doppler Shift in La_1.85Sr_0.15CuO₄/Au Junctions 招待有り査読有り

Hironori Teshima, Kang Donguhn, Takashi Sakamori, Rikizo Yano, Yuya Hiramatsu, Shun Tamura, Keiji Yada, Yukio Tanaka, Takao Sasagawa, and Satoshi Kashiwaya

Proceedings of the 29th International Conference on Low Temperature Physics (LT29) 38 巻頁： 011041 2023年5月

Two-Band Model and Point Contact Spectroscopy of Nodal-Line Semimetal CaAg0.9Pd0.1P 査読有り国際誌

Naoki Matsubara, Shota Nagasaka, Rikizo Yano, Kazushige Saigusa, Yusaku Shinoda, Yoshihiko Okamoto, Koshi Takenaka, Satoshi Kashiwaya

Proceedings of the 29th International Conference on Low Temperature Physics (LT29) 2023年5月

Andreev Bound States and Doppler Shift in La1.85Sr0.15CuO4/Au Junctions 査読有り国際誌

Hironori Teshima, Kang Donguhn, Takashi Sakamori, Rikizo Yano, Yuya Hiramatsu, Shun Tamura, Keiji Yada, Yukio Tanaka, Takao Sasagawa, Satoshi Kashiwaya

JPS Conf. Proc.: Proceedings of the 29th International Conference on Low Temperature Physics (LT29) 38 巻頁： 011041 2023年5月

Evaluation of Magnetic Field Induced by Broken Time-Reversal Symmetry Superconductors 査読有り国際誌

Mitsuhiro Teshigawara, Yasunori Mawatari, Hirotake Yamamori, Rikizo Yano, Satoshi Kashiwaya

JPS Conf. Proc.: Proceedings of the 29th International Conference on Low Temperature Physics (LT29) 38 巻頁： 011069 2023年5月

Transport Properties of Magnetically Doped Topological Insulator Fe-BiSbTe2Se 査読有り国際誌

Tsuyoshi Tanda, Rikizo Yano, Hishiro T. Hirose, Takao Sasagawa, Satoshi Kashiwaya

JPS Conf. Proc.: Proceedings of the 29th International Conference on Low Temperature Physics (LT29) 38 巻頁： 011180 2023年5月

Andreev Bound States and Doppler Shift in La1.85Sr0.15CuO4/Au Junctions 査読有り

矢野力三

JPS Conf. Proc. : 29th International Conference on LOW TEMPERATURE PHYSICS －巻 2023年

Proximity-Induced Superconducting States of Magnetically Doped 3D Topological Insulators with High Bulk Insulation 査読有り国際誌

Yano, R; Hirose, HT; Tsumura, K; Yamamoto, S; Koyanagi, M; Kanou, M; Kashiwaya, H; Sasagawa, T; Kashiwaya, S

CONDENSED MATTER 4 巻 ( 1 ) 頁： 1 - 9 2019年1月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Condensed Matter

We studied magnetized topological insulator/superconductor junctions with the expectation of unconventional superconductive states holding Majorana fermions induced by superconductive proximity effects on the surface states of magnetized topological insulators (TIs), attached by conventional superconductors. We introduced Fe-doped BiSbTe2 Se as an ideal magnetic TI and used the developed junction fabrication process to access the proximity-induced surface superconducting states. The bulk single crystals of the Fe-doped TI showed excellent bulk-insulating properties and ferromagnetism simultaneously at a low temperature. Meanwhile, the fabricated junctions also showed an insulating behavior above 100 K, as well as metallic conduction at a low temperature, which reflects bulk carrier freezing. In addition, we observed a proximity-induced gap structure in the conductance spectra. These results indicate that the junctions using the established materials and process are preferable to observe unconventional superconducting states which are induced via the surface channels of the magnetized TI. We believe that the developed process can be applied for the fabrication of complicated junctions and suites for braiding operations.

DOI： 10.3390/condmat4010009

Web of Science

Scopus

Extremely large magnetoresistance in a high-quality WTe2 grown by ﬂux method 査読有り

K.Tsumura, R. Yano, M. Koyanagi, H. Kashiwaya, S. Masubuchi, T. Machida, H. Namiki, T. Sasagawa, and S. Kashiwaya

J. Phys. Conf. Ser. 969 巻頁： 012134 2018年

Extremely large magnetoresistance in a high-quality WTe2 grown by flux method 査読有り国際誌

K. Tsumura, R. Yano, H. Kashiwaya, M. Koyanagi, S. Masubuchi, T. Machida, H. Namiki, T. Sasagawa, S. Kashiwaya

J. Phys. Conf. Ser.: 28TH INTERNATIONAL CONFERENCE ON LOW TEMPERATURE PHYSICS (LT28) 969 巻 2018年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IOP PUBLISHING LTD

We have grown single crystals of WTe2 by a self-flux method and evaluated the quality of the crystals. A Hall bar-type device was fabricated from an as-exfoliated film on a Si substrate and longitudinal resistance R-xx was measured. R-xx increased with an applied perpendicular magnetic field without saturation and an extremely large magnetoresistance as high as 376,059 % was observed at 8.27 T and 1.7 K.

DOI： 10.1088/1742-6596/969/1/012134

Web of Science

Narrow-band anisotropic electronic structure of ReS2 査読有り国際共著国際誌

D. Biswas, Alex M. Ganose, R. Yano, J. M. Riley, L. Bawden, O. J. Clark, J. Feng, L. Collins-Mcintyre, M. T. Sajjad, W. Meevasana, T. K. Kim, M. Hoesch, J. E. Rault, T. Sasagawa, David O. Scanlon, P. D. C. King

PHYSICAL REVIEW B 96 巻 ( 8 ) 頁： 085205 - 085205 2017年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER PHYSICAL SOC

We have used angle-resolved photoemission spectroscopy to investigate the band structure of ReS2, a transitionmetal dichalcogenide semiconductor with a distorted 1T crystal structure. We find a large number of narrow valence bands, which we attribute to the combined influence of structural distortion and spin-orbit coupling. We further show how this leads to a strong in-plane anisotropy of the electronic structure, with quasi-one-dimensional bands reflecting predominant hopping along zigzag Re chains. We find that this does not persist up to the top of the valence band, where a more three-dimensional character is recovered with the fundamental band gap located away from the Brillouin zone center along k(z). These experiments are in good agreement with our density-functional theory calculations, shedding light on the bulk electronic structure of ReS2, and how it can be expected to evolve when thinned to a single layer.

DOI： 10.1103/PhysRevB.96.085205

Web of Science

Thermoelectric Properties in Single Crystals of Non-stoichiometric Compounds Ag_xCr_2+y(S,Se)₄ (x ~ 0.74, y ~ 0.42) 査読有り

Rikizo Yano and Takao Sasagawa

Science of Advanced Materials 8 巻頁： 2077 2016年

Crystal Growth and Properties of ACrX₂ (A = Cu, Ag; X = S, Se) without a Secondary Phase 査読有り

Rikizo Yano and Takao Sasagawa

Crystal Growth and Design 16 巻頁： 5618 2016年

　前のページ - 次のページ　

<矢野 力三>

論文 - 矢野 力三

<矢野　力三>

論文 - 矢野　力三