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Tokunaga, Yo; Aoki, Dai*; Mayaffre, H.*; Kr
mer, S.*; Julien, M.-H.*; Berthier, C.*; Horvati
, M.*; Sakai, Hironori; Kambe, Shinsaku; Hattori, Taisuke; et al.
JPS Conference Proceedings (Internet), 30, p.011037_1 - 011037_6, 2020/03
The field-angular dependence of Co-NMR spin-lattice relaxation rate 
has been measured for a 10% Co-doped single crystal of URhGe. The experiment revealed that spin fluctuations in ferromagnetic (FM) state of URhGe are robust against magnetic field below about 4 T, applied along any direction in the 
crystal plane. This is in clear contrast with the sister compound UCoGe, in which FM spin fluctuations are rapidly suppressed by a tiny applied field along the 
axis. We show that such a difference in the character of the spin fluctuations is reflected in their two distinct phase diagrams for the upper critical field 
, providing further support to the mechanism of superconductivity mediated by spin fluctuations in these materials.
Tokunaga, Yo; Aoki, Dai*; Mayaffre, H.*; Krmer, S.*; Julien, M.-H.*; Berthier, C.*; Horvati, M.*; Sakai, Hironori; Hattori, Taisuke; Kambe, Shinsaku; et al.
Physical Review B, 93(20), p.201112_1 - 201112_5, 2016/05
Times Cited Count：14 Percentile：54.92(Materials Science, Multidisciplinary)The ferromagnetic superconductor URhGe has been known to exhibit an extremely large enhancement of the upper critical field when the field is confined and rotated in the (
) crystal plane. Our high-field 
Co NMR measurements on 10% Co-doped URhGe up to 30 T prove that this unconventional behavior of the superconductivity (SC) is associated with a strong anisotropy of field-dependent quantum fluctuations near a tricritical point. These fluctuations are rapidly suppressed by the field component along the axis, while being unaffected by any field component along the 
axis. The observed close interplay between the SC and quantum fluctuations strongly supports a pairing mechanism mediated by these fluctuations in URhGe.
Tokunaga, Yo; Aoki, Dai*; Mayaffre, H.*; Krmer, S.*; Julien, M.-H.*; Berthier, C.*; Horvati, M.*; Sakai, Hironori; Kambe, Shinsaku; Hattori, Taisuke; et al.
Journal of Physics; Conference Series, 683(1), p.012010_1 - 012010_6, 2016/02
Times Cited Count：0 Percentile：0.03(Materials Science, Multidisciplinary)Metamagnetism is in itself quite interesting phenomena, especially in a system with itinerant f-electrons. Unconventional states observed in the vicinity of the metamagnetic transition have been the subject of a number of recent publications. The object of this study is to elucidate the interplay between superconductivity and metamagnetism in URhGe. The nature of the metamagnetism becomes particularly important in ferromagnetic superconductors URhGe and UCoGe, since it is likely related to the pairing mechanism for their unconventional superconductivity. Here we report the result of our Co-NMR study on URh
Co
Ge and discuss the origin of the field induced superconducting phenomenon observed in high fields around 12 T.
Co NMR in URh
Co
GeTokunaga, Yo; Aoki, Dai*; Mayaffre, H.*; Krmer, S.*; Julien, M.-H.*; Berthier, C.*; Horvati, M.*; Sakai, Hironori; Kambe, Shinsaku; Araki, Shingo*
Physical Review Letters, 114(21), p.216401_1 - 216401_5, 2015/05
Times Cited Count：51 Percentile：89.51(Physics, Multidisciplinary)Our measurements of the Co NMR spin-spin relaxation in URhCoGe reveal a divergence of electronic spin fluctuations in the vicinity of the field-induced quantum critical point at 
T, around which reentrant superconductivity (RSC) occurs in the ferromagnetic heavy fermion compound URhGe. We show that critical fluctuations develop in the same limited region near the field 
as that where RSC is observed. This strongly suggests these quantum fluctuations as the pairing glue responsible for the RSC. The fluctuations observed are characteristic of a tricritical point.
P
Araki, Shingo*; Hayashida, Minami*; Nishiumi, Naoto*; Manabe, Hiroki*; Ikeda, Yoichi*; Kobayashi, Tatsuo*; Murata, Keizo*; Inada, Yoshihiko*; Wi
niewski, P.*; Aoki, Dai*; et al.
Journal of the Physical Society of Japan, 84(2), p.024705_1 - 024705_8, 2015/02
Times Cited Count：9 Percentile：55.91(Physics, Multidisciplinary)P under high pressureAraki, Shingo*; Hayashida, Minami*; Nishiumi, Naoto*; Manabe, Hiroki*; Ikeda, Yoichi*; Kobayashi, Tatsuo*; Murata, Keizo*; Inada, Yoshihiko*; Winiewski, P.*; Aoki, Dai*; et al.
JPS Conference Proceedings (Internet), 3, p.011081_1 - 011081_6, 2014/06
(R: Rare earth)Hieu, N. V.*; Takeuchi, Tetsuya*; Shishido, Hiroaki*; Tonohiro, Chie*; Yamada, Tsutomu*; Nakashima, Hiroshi*; Sugiyama, Kiyohiro*; Settai, Rikio*; Matsuda, Tatsuma; Haga, Yoshinori; et al.
Journal of the Physical Society of Japan, 76(6), p.064702_1 - 064702_16, 2007/06
Times Cited Count：49 Percentile：84.5(Physics, Multidisciplinary)
In-NQR study of antiferromagnetism and superconductivity in CeRhIn and CeIn under pressureKawasaki, Shinji*; Yashima, Mitsuharu*; Kotegawa, Yu*; Mito, Takeshi*; Kawasaki, Yu*; Zheng, G.-Q.*; Kitaoka, Yoshio*; Shishido, Hiroaki*; Araki, Shingo*; Aoki, Dai*; et al.
Journal of Physics and Chemistry of Solids, 67(1-3), p.497 - 499, 2006/01
Times Cited Count：2 Percentile：13.65(Chemistry, Multidisciplinary)We report the novel phase diagram of superconductivity (SC) and antiferromagnetism (AFM) in heavy-fermion (HF) pressure (
)-induced superconductors CeRhIn and CeIn through nuclear-quadrupole-resonance (NQR) measurements under . The -induced superconductivity in CeRhIn coexists with AFM on a microscopic level in 1.5-1.9 GPa. By contrast, in CeIn, the -induced phase separation of AFM and paramagnetism (PM) takes place without any trace of a quantum phase transition. The outstanding finding is that SC sets in at both the phasesmagnetically separated into AFM and PM in 2.28-2.5 GPa.
(T: Co, Rh, and Ir)Hieu, N. V.*; Shishido, Hiroaki*; Thamizhavel, A.*; Settai, Rikio*; Araki, Shingo*; Nozue, Yasuo*; Matsuda, Tatsuma; Haga, Yoshinori; Takeuchi, Tetsuya*; Harima, Hisatomo*; et al.
Journal of the Physical Society of Japan, 74(12), p.3320 - 3328, 2005/12
Times Cited Count：13 Percentile：59.33(Physics, Multidisciplinary)We grew single crystals of PrCoIn, PrRhIn, and PrIrIn with the tetragonal crystal structure and measured the electrical resistivity, specific heat, magnetic susceptibility, magnetization and de Haas-van Alphen effect. These Pr compounds reveal no magnetic ordering. The topology of the Fermi surfaces is the same as that of a non-4 f reference compound LaRhIn. The cyclotron mass and/or the electronic specific heat coefficient are also approximately the same as those of LaRhIn. The magnetic susceptibility and magnetization are anisotropic, reflecting the crystal structure, which are well explained by the tetragonal crystalline electric field scheme with the singlet ground state.
Sb
Kuwahara, Keitaro*; Iwasa, Kazuaki*; Kogi, Masafumi*; Kaneko, Koji; Araki, Shingo; Metoki, Naoto; Sugawara, Hitoshi*; Aoki, Yuji*; Sato, Hideyuki*
Journal of the Physical Society of Japan, 73(6), p.1438 - 1441, 2004/06
Times Cited Count：64 Percentile：87.39(Physics, Multidisciplinary)no abstracts in English
SbMetoki, Naoto; Kaneko, Koji; Araki, Shingo; Kogi, Masafumi*; Iwasa, Kazuaki*; Kuwahara, Keitaro*; Bernhoeft, N.*; Mignot, J.-M.*; Gukasov, A.*; Sato, Hideyuki*; et al.
Journal of Magnetism and Magnetic Materials, 272-276(Suppl.), p.e91 - e92, 2004/05
Times Cited Count：1 Percentile：7.12(Materials Science, Multidisciplinary)no abstracts in English
Araki, Shingo; Metoki, Naoto; Thamizhavel, A.*; Onuki, Yoshichika
Journal of Physics; Condensed Matter, 15(23), p.S2179 - S2182, 2003/07
no abstracts in English
Pd
Si
Metoki, Naoto; Koike, Yoshihiro; Haga, Yoshinori; Kaneko, Koji; Araki, Shingo; McEwen, K. A.*; Kogi, Masafumi*; Aso, Naofumi*; Lander, G. H.; Komatsubara, Takemi*; et al.
Journal of Physics; Condensed Matter, 15(28), p.S1957 - S1963, 2003/07
Times Cited Count：2 Percentile：15.16(Physics, Condensed Matter)no abstracts in English
-localized ferromagnet CeAgSbAraki, Shingo; Metoki, Naoto; Galatanu, A.; Yamamoto, Etsuji; Thamizhavel, A.*; Onuki, Yoshichika
Physical Review B, 68(2), p.024408_1 - 024408_9, 2003/07
Times Cited Count：46 Percentile：84.84(Materials Science, Multidisciplinary)no abstracts in English
SbKogi, Masafumi*; Iwasa, Kazuaki*; Nakajima, Motoki*; Metoki, Naoto; Araki, Shingo; Bernhoeft, N.*; Mignot, J.-M.*; Gukasov, A.*; Sato, Hideyuki*; Aoki, Yuji*; et al.
Journal of the Physical Society of Japan, 72(5), p.1002 - 1005, 2003/05
Times Cited Count：199 Percentile：97.23(Physics, Multidisciplinary)no abstracts in English
Si under pressureAraki, Shingo; Nakashima, Miho*; Settai, Rikio*; Kobayashi, Tatsuo*; Onuki, Yoshichika
Acta Physica Polonica B, 34(2, Part1), p.439 - 442, 2003/02
no abstracts in English
Homma, Tetsuo; Yamamoto, Etsuji; Haga, Yoshinori; Settai, Rikio*; Araki, Shingo*; Inada, Yoshihiko*; Takeuchi, Tetsuya*; Kuwahara, Keitaro*; Amitsuka, Hiroshi*; Sakakibara, T.*; et al.
Physica B; Condensed Matter, 281-282, p.195 - 196, 2000/06
Times Cited Count：2 Percentile：15.67(Physics, Condensed Matter)no abstracts in English
Haga, Yoshinori; Yamamoto, Etsuji; Homma, Tetsuo*; Nakamura, Akio; *; Araki, Shingo*; Okuni, H.*; Onuki, Yoshichika*
Physica B; Condensed Matter, 259-261, p.627 - 628, 1999/00
Times Cited Count：18 Percentile：66.48(Physics, Condensed Matter)no abstracts in English
Co)Ge, 3Tokunaga, Yo; Aoki, Dai*; Mayaffre, H.*; Krmer, S.*; Julien, M.-H.*; Berthier, C.*; Horvati, M.*; Hattori, Taisuke; Sakai, Hironori; Kambe, Shinsaku; et al.
no journal, ,
no abstracts in English
Tokunaga, Yo; Aoki, Dai*; Mayaffre, H.*; Krmer, S.*; Julien, M.-H.*; Berthier, C.*; Horvati, M.*; Hattori, Taisuke; Sakai, Hironori; Kambe, Shinsaku; et al.
no journal, ,
no abstracts in English
Tokunaga, Yo; Aoki, Dai*; Mayaffre, H.*; Krmer, S.*; Julien, M.-H.*; Berthier, C.*; Horvati, M.*; Sakai, Hironori; Hattori, Taisuke; Kambe, Shinsaku; et al.
no journal, ,
Ferromagnetism is incompatible in general with superconductivity (SC) with singlet spin pairs, since a strong exchange field in ferromagnetic state forces the spin pairs to align in the same direction. In contrast, fluctuation of ferromagnetic moments has been supposed to create a binding force between quasi-particles with triplet spin. Such an unconventional spin-triplet state, mediated by ferromagnetic fluctuations, is now expected to be realized in a family of uranium based compounds, UGe
, URhGe and UCoGe, so far the only fully established examples of ferromagnetic superconductors in which uniform SC is realized deep inside the ferromagnetic states. To elucidate the mechanism of this exotic SC, we have prepared a URhGe single crystal and performed nuclear magnetic resonance (NMR) experiments.
