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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.
Te-NMR study on a single crystal of heavy fermion superconductor UTe
Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Hattori, Taisuke; Higa, Nonoka; Nakamine, Genki*; Kitagawa, Shunsaku*; Ishida, Kenji*; Nakamura, Ai*; Shimizu, Yusei*; et al.
Journal of the Physical Society of Japan, 88(7), p.073701_1 - 073701_4, 2019/07
Times Cited Count：58 Percentile：94.69(Physics, Multidisciplinary)We report Te-NMR studies on a newly discovered heavy fermion superconductor UTe. Using a single crystal, we have measured the Te-NMR Knight shift 
and spin-lattice relaxation rate for fields along the three orthorhombic crystal axes. The data confirm a moderate Ising anisotropy for both the static () and dynamical susceptibilities () in the paramagnetic state above about 20 K. Around 20 K, however, we have observed a sudden loss of NMR spin-echo signal due to sudden enhancement of the NMR spin-spin relaxation rate 
, when the field is applied along the easy axis of magnetization (=
axis). This behavior suggests the development of longitudinal magnetic fluctuations along the axis at very low frequencies below 20 K.
-electron systems with filled skutterudite structureHotta, Takashi
Journal of the Physical Society of Japan, 74(4), p.1275 - 1288, 2005/04
Times Cited Count：25 Percentile：72.91(Physics, Multidisciplinary)In order to understand electronic properties of filled skutterudite materials, the Anderson model is analyzed by using the numerical renormalization group method to evaluate magnetic susceptibility and entropy of electron for each case of 
=1
13, where is the number of electrons per rare-earth ion. For the 
-electron system corresponding to the Pr-based filled skutterudite, it is found that magnetic fluctuations significantly remain at low temperatures, even when the ground state is 
singlet, if 
triplet is the excited state with small excitation energy. By analyzing an orbital degenerate Hubbard model constructed based on the 
- coupling scheme, we find that anisotropic Cooper-pair mediated by magnetic fluctuations appears in a limited region in which the singlet and triplet ground states are interchanged.
-electron systemsHotta, Takashi
Physica B; Condensed Matter, 359-361, p.1003 - 1005, 2005/04
Times Cited Count：1 Percentile：6.23(Physics, Condensed Matter)In order to understand magnetic properties of filled skutterudite materials, we evaluate magnetic susceptibility of the Anderson model with orbital degeneracy by using the numerical renormalization group method. Even when the local ground state is , magnetic fluctuations significantly remain, if is the excited state with small excitation energy, as experimentally proposed for Pr-based filled skutterudite compounds.
Hotta, Takashi
Physical Review Letters, 94(6), p.067003_1 - 067003_4, 2005/02
Times Cited Count：15 Percentile：62.72(Physics, Multidisciplinary)In order to clarify magnetic properties of filled skutterudites, we analyze the Anderson model including seven orbitals hybridized with an 
conduction band using a numerical technique. For =2 corresponding to Pr-based filled skutterudites, where is the local -electron number, even if the ground state is a singlet, there remain significant magnetic fluctuations from a triplet state with a small excitation energy. This result can be understood by the fact that -electron states are clearly distinguished as itinerant and localized ones in the filled skutterudite structure. This picture also explains the complex results for -electron magnetic susceptibility and entropy for =113.
Ga
Abe, Hideki*; Yoshii, Kenji; Kitazawa, Hideaki*
Journal of the Physical Society of Japan, 70(10), p.3042 - 3045, 2001/10
Times Cited Count：9 Percentile：51.43(Physics, Multidisciplinary)no abstracts in English
Tokunaga, Yo; Sakai, Hironori; Kambe, Shinsaku; Opletal, P.; Tokiwa, Yoshifumi; Haga, Yoshinori
no journal, ,
no abstracts in English
