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; Improvement of 
and multiple superconducting phase diagramSakai, Hironori; Haga, Yoshinori
Kotai Butsuri, 58(10), p.529 - 536, 2023/10
We have succeeded to grow high-quality UTe single crystals with excess uranium through molten salt flux method. We have also studied the superconducting phase diagram using the high-quality crystal applying the fields up to 25 T along the magnetic hard 
axis.
along hard magnetic axisSakai, Hironori; Tokiwa, Yoshifumi; Opletal, P.; Kimata, Motoi*; Awaji, Satoshi*; Sasaki, Takahiko*; Aoki, Dai*; Kambe, Shinsaku; Tokunaga, Yo; Haga, Yoshinori
Physical Review Letters, 130(19), p.196002_1 - 196002_6, 2023/05
Times Cited Count：6 Percentile：93.15(Physics, Multidisciplinary)The superconducting (SC) phase diagram in uranium ditelluride is explored under magnetic fields (
) along the hard magnetic -axis using a high-quality single crystal with = 2.1 K. Simultaneous electrical resistivity and AC magnetic susceptibility measurements discern low- and high-field SC (LFSC and HFSC, respectively) phases with contrasting field-angular dependence. Crystal quality increases the upper critical field of the LFSC phase, but the 
of 
T, at which the HFSC phase appears, is always the same through the various crystals. A phase boundary signature is also observed inside the LFSC phase near , indicating an intermediate SC phase characterized by small flux pinning forces.
Ni
In
Sakai, Hironori; Tokunaga, Yo; Kambe, Shinsaku; Zhu, J.-X.*; Ronning, F.*; Thompson, J. D.*; Kotegawa, Hisashi*; To, Hideki*; Suzuki, Kohei*; Oshima, Yoshiki*; et al.
Physical Review B, 106(23), p.235152_1 - 235152_8, 2022/12
Times Cited Count：0 Percentile：0(Materials Science, Multidisciplinary)We investigate the electronic state of Ni-substituted CeCoNi
In by nuclear quadrupole and magnetic resonance (NQR/NMR) techniques. The heavy fermion superconductivity below 
K for 
is suppressed by Ni substitutions, and reaches zero for 
. The 
In NQR spectra for 
and 0.25 can be explained by simulating the electrical field gradient that is calculated for a virtual supercell with density functional theory. The spin-lattice relaxation rate 
indicates that Ni substitution weakens antiferromagnetic correlations that are not localized near the substituent but instead are uniform in space. The temperature (
) dependence of 
for shows a maximum around 
K and decreases toward almost zero when temperature is further reduced as if a gap might be opening in the magnetic excitation spectrum; however, the magnetic specific heat and the static magnetic susceptibility evolve smoothly through 
with a 
dependence. The peculiar T dependence of and non-Fermi-liquid specific heat and susceptibility can be interpreted in a unified way by assuming nested antiferromagnetic spin fluctuations in a quasi-two-dimensional electronic system.
Funato, Takumi*; Yamakage, Ai*; Matsuo, Mamoru
Physical Review B, 106(21), p.214420_1 - 214420_7, 2022/12
Times Cited Count：1 Percentile：15.88(Materials Science, Multidisciplinary) by molten salt flux methodSakai, Hironori; Opletal, P.; Tokiwa, Yoshifumi; Yamamoto, Etsuji; Tokunaga, Yo; Kambe, Shinsaku; Haga, Yoshinori
Physical Review Materials (Internet), 6(7), p.073401_1 - 073401_10, 2022/07
Times Cited Count：18 Percentile：89.58(Materials Science, Multidisciplinary)The molten salt flux method is applied as a new synthetic route for the single crystals of the spin-triplet superconductor UTe. The single crystals under an optimized growth condition with excess uranium exhibit a superconducting transition at 
K, which is the highest reported for this compound. The obtained crystals show a remarkably large residual resistivity ratio with respect to the room temperature value and a small residual electronic contribution in specific heat well below . These results indicate that the increase of in UTe can be achieved by reducing the disorder associated with uranium vacancies. The excess uranium in the molten salt acts as a reducing agent, preventing tetravalent uranium from becoming pentavalent and suppressing creation of uranium vacancies. At the same time, the relatively low growth temperature can suppress Te volatilization.
-wave superconductor/ferromagnetic insulator bilayer systemsOminato, Yuya*; Yamakage, Ai*; Kato, Takeo*; Matsuo, Mamoru
Physical Review B, 105(20), p.205406_1 - 205406_7, 2022/05
Times Cited Count：9 Percentile：79.16(Materials Science, Multidisciplinary) under pressure revealed by 
Te-NMRKinjo, Katsuki*; Fujibayashi, Hiroki*; Nakamine, Genki*; Kitagawa, Shunsaku*; Ishida, Kenji*; Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Nakamura, Ai*; Shimizu, Yusei*; et al.
Physical Review B, 105(14), p.L140502_1 - L140502_5, 2022/04
Times Cited Count：5 Percentile：64.66(Materials Science, Multidisciplinary)
-type La
Eu
CuO
and Nd
CuOAsano, Shun*; Ishii, Kenji*; Matsumura, Daiju; Tsuji, Takuya; Kudo, Kota*; Taniguchi, Takanori*; Saito, Shin*; Sunohara, Toshiki*; Kawamata, Takayuki*; Koike, Yoji*; et al.
Physical Review B, 104(21), p.214504_1 - 214504_7, 2021/12
Times Cited Count：1 Percentile：0(Materials Science, Multidisciplinary)Te NMR on UTeNakamine, Genki*; Kinjo, Katsuki*; Kitagawa, Shunsaku*; Ishida, Kenji*; Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Nakamura, Ai*; Shimizu, Yusei*; Homma, Yoshiya*; et al.
Journal of the Physical Society of Japan, 90(6), p.064709_1 - 064709_7, 2021/06
Times Cited Count：18 Percentile：85.69(Physics, Multidisciplinary) probed with Te-NMR measurementNakamine, Genki*; Kinjo, Katsuki*; Kitagawa, Shunsaku*; Ishida, Kenji*; Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Nakamura, Ai*; Shimizu, Yusei*; Homma, Yoshiya*; et al.
Physical Review B, 103(10), p.L100503_1 - L100503_5, 2021/03
Times Cited Count：34 Percentile：93.21(Materials Science, Multidisciplinary)Shamoto, Shinichi
Koon Chodendo No Wakaki Samuraitachi; Nihonjin Kenkyusha No Chosen To Funto No Kiroku, p.105 - 121, 2019/12
no abstracts in English
As and LiFeAs by X-ray PDF and XAFS analysesLi, S.*; Toyoda, Masayuki*; Kobayashi, Yoshiaki*; Ito, Masayuki*; Ikeuchi, Kazuhiko*; Yoneda, Yasuhiro; Otani, Akira*; Matsumura, Daiju; Asano, Shun*; Mizuki, Junichiro*; et al.
Physica C, 555, p.45 - 53, 2018/12
Times Cited Count：1 Percentile：4.99(Physics, Applied)
-dependence of local distortions in BaFeAs and LiFeAs by X-ray PDF and XAFS methods. Although PDF data exhibit anomaly at the structure transition temperature, EXAFS data exhibit no anomaly. Data supporting the local orthorhombicity at 300 K in the tetragonal phase for BaFeAs. Arguments on the origins of the 4-fold symmetry breaking in the ground average structure of the tetragonal phase.
CeCuO
studied by Cu 
-edge X-ray absorption spectroscopyAsano, Shun*; Ishii, Kenji*; Matsumura, Daiju; Tsuji, Takuya; Ina, Toshiaki*; Suzuki, Kensuke*; Fujita, Masaki*
Journal of the Physical Society of Japan, 87(9), p.094710_1 - 094710_5, 2018/09
Times Cited Count：13 Percentile：64.6(Physics, Multidisciplinary)-edge XAFS for electron-doped cuprate superconductorsAsano, Shun*; Suzuki, Kensuke*; Matsumura, Daiju; Ishii, Kenji*; Ina, Toshiaki*; Fujita, Masaki*
Journal of Physics; Conference Series, 969, p.012051_1 - 012051_5, 2018/04
Times Cited Count：3 Percentile：81.88(Physics, Applied)Ge in the normal stateNakatani, Yasuhiro*; Aratani, Hidekazu*; Fujiwara, Hidenori*; Mori, Takeo*; Tsuruta, Atsushi*; Tachibana, Shoichi*; Yamaguchi, Takashi*; Kiss, Takayuki*; Yamasaki, Atsushi*; Yasui, Akira*; et al.
Physical Review B, 97(11), p.115160_1 - 115160_7, 2018/03
Times Cited Count：5 Percentile：25.53(Materials Science, Multidisciplinary)
Nomura, Takuji*; Harada, Yoshihisa*; Niwa, Hideharu*; Ishii, Kenji*; Ishikado, Motoyuki*; Shamoto, Shinichi; Jarrige, I.*
Physical Review B, 94(3), p.035134_1 - 035134_9, 2016/07
Times Cited Count：11 Percentile：46.82(Materials Science, Multidisciplinary)Low-energy electron excitation spectra were measured on a single crystal of a typical iron-based superconductor PrFeAsO using resonant inelastic X-ray scattering (RIXS) at the Fe-
edge.
Furuki, Yuichi*; Sueyoshi, Tetsuro*; Kai, Takashi*; Iwanaga, Yasuya*; Fujiyoshi, Takanori*; Ishikawa, Norito
Physica C, 518, p.58 - 62, 2015/11
Times Cited Count：4 Percentile：19.27(Physics, Applied)In order to reveal the influence of crossing angle of one-dimensional pinning centers on angular dependence of critical current density Jc, heavy-ion irradiation was performed to introduce columnar defects (CDs) crossing relative to the c-axis into GdBCO coated conductors, where the splay plane consisting of the two directions of CDs is parallel to the current flow direction. For the sample containing CDs with 15
, a single and sharp peak was observed around B
c in the angular dependence of Jc. When the crossing angle was extended to 45, the single Jc-peak became broader, which was a gently-sloping mountain-like shape centered at Bc. For 75, on the other hand, a quite different behaviour of Jc from the other irradiated samples was observed, which was analogous to the angular dependence of Jc typical of three dimensional pinning centers.
Sueyoshi, Tetsuro*; Kotaki, Tetsuya*; Furuki, Yuichi*; Uraguchi, Yusei*; Kai, Takashi*; Fujiyoshi, Takanori*; Shimada, Yusuke*; Yasuda, Kazuhiro*; Ishikawa, Norito
IEEE Transactions on Applied Superconductivity, 25(3), p.6603004_1 - 6603004_4, 2015/06
Times Cited Count：11 Percentile：50.43(Engineering, Electrical & Electronic)To investigate the effect of discontinuity of 1-D pinning centers on the flux pinning in a wide range of magnetic field directions, discontinuous columnar defects (CDs) and continuous CDs were formed in GdBCO coated conductors using Xe-ion irradiations with 80 and 270 MeV, respectively. An overall shift upward in Jc, for the 80-MeV-irradiated sample compared to the 270-MeV-irradiated one, can be observed in every direction of magnetic field, which is more remarkable as temperature decreases. This implies a synergetic effect of the pinning interaction between the linearity and the discontinuity for the discontinuous CDs.
superconductorMachida, Masahiko; Koyama, Tomio*; Kato, Masaru*; Ishida, Takekazu*
Nuclear Instruments and Methods in Physics Research A, 559(2), p.594 - 596, 2006/04
Times Cited Count：11 Percentile：60.11(Instruments & Instrumentation)no abstracts in English
Machida, Masahiko; Koyama, Tomio*; Kato, Masaru*; Ishida, Takekazu*
Physica C, 426-431(1), p.169 - 173, 2005/10
no abstracts in English
