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Journal Articles

Polarization dependence of soft X-ray absorption spectroscopy on the heavy fermion superconductor CeNi$$_{2}$$Ge$$_{2}$$

Fujiwara, Hidenori*; Nakatani, Yasuhiro*; Aratani, Hidekazu*; Kanai-Nakata, Yuina*; Yamagami, Kohei*; Hamamoto, Satoru*; Kiss, Takayuki*; Sekiyama, Akira*; Tanaka, Arata*; Ebihara, Takao*; et al.

New Physics; Sae Mulli, 73(12), p.1062 - 1066, 2023/12

Journal Articles

Longitudinal spin fluctuations driving field-reinforced superconductivity in UTe$$_2$$

Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Opletal, P.; Tokiwa, Yoshifumi; Haga, Yoshinori; Kitagawa, Shunsaku*; Ishida, Kenji*; Aoki, Dai*; Knebel, G.*; et al.

Physical Review Letters, 131(22), p.226503_1 - 226503_7, 2023/12

 Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)

Journal Articles

High quality single crystal growth of a novel superconductor UTe$$_2$$; Improvement of $$T_{rm c}$$ and multiple superconducting phase diagram

Sakai, Hironori; Haga, Yoshinori

Kotai Butsuri, 58(10), p.529 - 536, 2023/10

We have succeeded to grow high-quality UTe$$_2$$ 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 $$b$$ axis.

Journal Articles

Impact of the ground-state 4${it f}$ symmetry for anisotropic ${it cf}$ hybridization in the heavy-fermion superconductor CeNi$$_{2}$$Ge$$_{2}$$

Fujiwara, Hidenori*; Nakatani, Yasuhiro*; Aratani, Hidekazu*; Kanai, Yuina*; Yamagami, Kohei*; Hamamoto, Satoru*; Kiss, Takayuki*; Yamasaki, Atsushi*; Higashiya, Atsushi*; Imada, Shin*; et al.

Physical Review B, 108(16), p.165121_1 - 165121_10, 2023/10

 Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)

Journal Articles

Superconducting spin reorientation in spin-triplet multiple superconducting phases of UTe$$_2$$

Kinjo, Katsuki*; Fujibayashi, Hiroki*; Matsumura, Hiroki*; Hori, Fumiya*; Kitagawa, Shunsaku*; Ishida, Kenji*; Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Nakamura, Ai*; et al.

Science Advances (Internet), 9(30), p.2736_1 - 2736_6, 2023/07

 Times Cited Count:0 Percentile:0(Multidisciplinary Sciences)

Journal Articles

Low-temperature magnetic fluctuations investigated by $$^{125}$$Te-NMR on the uranium-based superconductor UTe$$_2$$

Fujibayashi, Hiroki*; Kinjo, Katsuki*; Nakamine, Genki*; Kitagawa, Shunsaku*; Ishida, Kenji*; Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Nakamura, Ai*; Shimizu, Yusei*; et al.

Journal of the Physical Society of Japan, 92(5), p.053702_1 - 053702_5, 2023/05

 Times Cited Count:2 Percentile:80.44(Physics, Multidisciplinary)

Journal Articles

Large reduction in the $$a$$-axis knight shift on UTe$$_2$$ with $$T_c$$ = 2.1 K

Matsumura, Hiroki*; Fujibayashi, Hiroki*; Kinjo, Katsuki*; Kitagawa, Shunsaku*; Ishida, Kenji*; Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Nakamura, Ai*; Shimizu, Yusei*; et al.

Journal of the Physical Society of Japan, 92(6), p.063701_1 - 063701_5, 2023/05

 Times Cited Count:5 Percentile:92.42(Physics, Multidisciplinary)

Journal Articles

Field induced multiple superconducting phases in UTe$$_2$$ along hard magnetic axis

Sakai, 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:5 Percentile:92.42(Physics, Multidisciplinary)

The superconducting (SC) phase diagram in uranium ditelluride is explored under magnetic fields ($$H$$) along the hard magnetic $$b$$-axis using a high-quality single crystal with $$T_{rm c}$$ = 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 $$H^{ast}$$ of $$sim15$$ 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 $$H^{ast}$$, indicating an intermediate SC phase characterized by small flux pinning forces.

Journal Articles

Physics of spin-triplet superconductivity in uranium compounds studied by NMR

Tokunaga, Yo; Sakai, Hironori; Kitagawa, Shunsaku*; Ishida, Kenji*

Nihon Butsuri Gakkai-Shi, 78(5), p.267 - 272, 2023/04

no abstracts in English

Journal Articles

Change of superconducting character in UTe$$_{2}$$ induced by magnetic field

Kinjo, Katsuki*; Fujibayashi, Hiroki*; Kitagawa, Shunsaku*; Ishida, Kenji*; Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Nakamura, Ai*; Shimizu, Yusei*; Homma, Yoshiya*; et al.

Physical Review B, 107(6), p.L060502_1 - L060502_5, 2023/02

 Times Cited Count:7 Percentile:93.16(Materials Science, Multidisciplinary)

Journal Articles

Present status of JAEA-Tokai tandem accelerator

Kabumoto, Hiroshi; Matsuda, Makoto; Nakamura, Masahiko; Ishizaki, Nobuhiro; Kutsukake, Kenichi; Otokawa, Yoshinori; Asozu, Takuhiro; Matsui, Yutaka; Nakagawa, Sohei; Abe, Shinichi

Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1109 - 1113, 2023/01

no abstracts in English

Journal Articles

Reports of electro-polishing implementation for quarter-wave resonators, 2

Nii, Keisuke*; Ida, Yoshiaki*; Ueda, Hideki*; Yamaguchi, Takanori*; Kabumoto, Hiroshi; Kamiya, Junichiro; Kondo, Yasuhiro; Tamura, Jun; Harada, Hiroyuki; Matsui, Yutaka; et al.

Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.601 - 604, 2023/01

no abstracts in English

Journal Articles

Nested antiferromagnetic spin fluctuations and non-Fermi-liquid behavior in electron-doped CeCo$$_{1-x}$$Ni$$_{x}$$In$$_5$$

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 CeCo$$_{1-x}$$Ni$$_x$$In$$_5$$ by nuclear quadrupole and magnetic resonance (NQR/NMR) techniques. The heavy fermion superconductivity below $$T_{rm c} = 2.3$$ K for $$x = 0$$ is suppressed by Ni substitutions, and $$T_{rm c}$$ reaches zero for $$x = 0.25$$. The $$^{115}$$In NQR spectra for $$x = 0.125$$ 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 $$1/T_1$$ indicates that Ni substitution weakens antiferromagnetic correlations that are not localized near the substituent but instead are uniform in space. The temperature ($$T$$) dependence of $$(T_1T)^{-1}$$ for $$x = 0.25$$ shows a maximum around $$T_{rm g} = 2$$ K and $$(T_1T)^{-1}$$ 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 $$T_{rm g}$$ with a $$-ln T$$ dependence. The peculiar T dependence of $$(T_1T)^{-1}$$ 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.

Journal Articles

Acoustic spin transport by superconducting quasiparticles

Funato, Takumi*; Yamakage, Ai*; Matsuo, Mamoru

Physical Review B, 106(21), p.214420_1 - 214420_7, 2022/12

 Times Cited Count:1 Percentile:17.38(Materials Science, Multidisciplinary)

Journal Articles

Direct measurement of the evolution of magnetism and superconductivity toward the quantum critical point

Higemoto, Wataru; Yokoyama, Makoto*; Ito, Takashi; Suzuki, Taiga*; Raymond, S.*; Yanase, Yoichi*

Proceedings of the National Academy of Sciences of the United States of America, 119(49), p.e2209549119_1 - e2209549119_6, 2022/11

 Times Cited Count:0 Percentile:0(Multidisciplinary Sciences)

no abstracts in English

Journal Articles

Anisotropic superconducting spin transport at magnetic interfaces

Ominato, Yuya*; Yamakage, Ai*; Matsuo, Mamoru

Physical Review B, 106(16), p.L161406_1 - L161406_6, 2022/10

 Times Cited Count:7 Percentile:73.14(Materials Science, Multidisciplinary)

Journal Articles

Single crystal growth of superconducting UTe$$_2$$ by molten salt flux method

Sakai, 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:16 Percentile:88.61(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$$_2$$. The single crystals under an optimized growth condition with excess uranium exhibit a superconducting transition at $$T_{rm c}=2.1$$ K, which is the highest $$T_{rm c}$$ 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 $$T_{rm c}$$. These results indicate that the increase of $$T_{rm c}$$ in UTe$$_2$$ 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.

Journal Articles

Unconventional superconductivity in UTe$$_2$$

Aoki, Dai*; Brison, J.-P.*; Flouquet, J.*; Ishida, Kenji*; Knebel, G.*; Tokunaga, Yo; Yanase, Yoichi*

Journal of Physics; Condensed Matter, 34(24), p.243002_1 - 243002_41, 2022/06

 Times Cited Count:54 Percentile:87.73(Physics, Condensed Matter)

Journal Articles

Ferromagnetic resonance modulation in $$d$$-wave superconductor/ferromagnetic insulator bilayer systems

Ominato, Yuya*; Yamakage, Ai*; Kato, Takeo*; Matsuo, Mamoru

Physical Review B, 105(20), p.205406_1 - 205406_7, 2022/05

 Times Cited Count:8 Percentile:77.62(Materials Science, Multidisciplinary)

Journal Articles

High density mapping systems for SRF cavities

Fuwa, Yasuhiro; Iwashita, Yoshihisa*; Kuriyama, Yasutoshi*; Tongu, Hiromu*; Hayano, Hitoshi*; Geng, R. L.*

Proceedings of 20th International Conference on RF Superconductivity (SRF 2021) (Internet), p.323 - 325, 2022/05

In order to evaluate the performance of a superconducting cavity, we are developing a mapping system to measure the distribution of cavity temperature, field emission X-rays, and trapped magnetic flux with high positional resolution. In order to construct a system with high positional resolution, a large number of sensors are required. However, as the number of sensors increases, so does the amount of wiring, which increases the complexity of the wiring in the cryogenic apparatus, and also increases the heat transfer through the wiring, which disturb efficient operation of cavity tests. We are developing an efficient mapping system with a multiplexer that scans the readout signal on the same circuit as the sensor in the cryogenic dewar where the cavity test is conducted. In this presentation, we report the outline and test results of the mapping system under development

532 (Records 1-20 displayed on this page)