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Ca
Cu
O
superconductorTokiwa, Kazuyasu*; Mikusu, Satoshi*; Higemoto, Wataru; Nishiyama, Kusuo*; Iyo, Akira*; Tanaka, Yasumoto*; Kotegawa, Hisashi*; Mukuda, Hidekazu*; Kitaoka, Yoshio*; Watanabe, Tsuneo*
Physica C, 460-462(2), p.892 - 895, 2007/09
Times Cited Count：3 Percentile：17.18(Physics, Applied)Zero- and longitudinal-field muon-spin rotation (ZF-
SR and LF-SR) measurements were carried out on a multi-layered HgBaCaCuO (Hg-1245) superconductor with 
of 108 K. With decreasing temperature, the observed ZF-SR function changed from a Gaussian-type to an exponential-type below 60 K and zero field muon precession was also observed below 45 K. These SR signals are attributed to the development of the antiferromagnetic ordering in inner CuOplanes with a low carrier concentration. These results seem to indicate clear evidence that antiferromagnetism microscopically coexists with superconductivity in the Hg-1245 superconductor below 60 K.
; A 
Ge-nuclear-quadrupole-resonance study under pressureHarada, Atsushi*; Kawasaki, Shinji*; Mukuda, Hidekazu*; Kitaoka, Yoshio*; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika; Ito, Kohei*; Haller, E. E.*; Harima, Hisatomo*
Physical Review B, 75(14), p.140502_1 - 140502_4, 2007/04
Times Cited Count：28 Percentile：71.28(Materials Science, Multidisciplinary)This paper reports that a different type of superconducting order parameter has been realized in the ferromagnetic states in UGe via Ge-nuclear-quadrupole-resonance experiments performed under pressure. Measurements of the nuclear spin-lattice relaxation rate (1/
) have revealed an unconventional nature of superconductivity such that the up-spin band is gapped with line nodes, but the down-spin band remains gapless at the Fermi level. This result is consistent with that of a ferromagnetic spin-pairing model in which Cooper pairs are formed among ferromagnetically polarized electrons. The present experiment has shed light on the possible origin of ferromagnetic superconductivity, which is mediated by ferromagnetic spin-density fluctuations relevant to the first-order transition inside the ferromagnetic states.
; Ge-NQR study under pressureHarada, Atsushi*; Kawasaki, Shinji*; Mukuda, Hidekazu*; Kitaoka, Yoshio*; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika; Ito, Kohei*; Haller, E. E.*; Harima, Hisatomo*
Physica B; Condensed Matter, 378-380, p.963 - 964, 2006/05
Times Cited Count：1 Percentile：6.19(Physics, Condensed Matter)The superconducting characteristics on the itinerant ferromagnetic superconductor UGe have been investigated via the Ge-NQR measurements under pressure (
) near the critical pressure 
where the first-order transition takes place from the low-temperature () and low- ferromagnetic phase (FM2) to high- and high- one (FM1). The measurements of nuclear spin-lattice relaxation rate 
have revealed a power-law like behavior as 
without the coherence peak, whereas at low temperatures, it deviates from the dependence to a -linear like behavior. These results that depend on the pressure are well understood in terms of non-unitary spin-triplet pairing state where the ferromagnetic up-spin band is gapped, but the down-spin band remains gapless at the Fermi level. We will argue an intimate relationship of the onset of SC with FM1 and FM2.
Pt-NMR study on noncentrosymmetric heavy-fermion superconductor CePt
SiYogi, Mamoru*; Kitaoka, Yoshio*; Hashimoto, Shin*; Yasuda, Takashi*; Settai, Rikio*; Matsuda, Tatsuma; Haga, Yoshinori; Onuki, Yoshichika; Rogl, P.*; Bauer, E.*
Journal of Physics and Chemistry of Solids, 67(1-3), p.522 - 524, 2006/01
Times Cited Count：9 Percentile：40.57(Chemistry, Multidisciplinary)We report on magnetic and novel superconducting properties in heavy-fermion (HF) noncentrosymmetric compound CePtSi via the measurement of Pt nuclear spin-lattice relaxation rate 1/
. This compound reveals the uniform coexistence of antiferromagnetism (
=2.2 K) and superconductivity (
=0.75 K). CePtSi is the first HF superconductor that reveals a peak in 1/ just below and, additionally, does not follow the 
law that was observed for most unconventional HF superconductors. The novel relaxation behavior found below may be relevant with a possible novel SC state being realized in the noncentrosymmetric CePtSi.
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：13.40(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.
Si; 
Si-NMR Knight shift studyYogi, Mamoru*; Mukuda, Hidekazu*; Kitaoka, Yoshio*; Hashimoto, Shin*; Yasuda, Takashi*; Settai, Rikio*; Matsuda, Tatsuma; Haga, Yoshinori; Onuki, Yoshichika; Rogl, P.*; et al.
Journal of the Physical Society of Japan, 75(1), p.013709_1 - 013709_4, 2006/01
Times Cited Count：64 Percentile：87.73(Physics, Multidisciplinary)We report the measurements of the Si Knight shift K
on the noncentrosymmetric heavy-fermion compound CePtSi in which antiferromagnetism (AFM) with 
=2.2 K coexists with superconductivity (SC) with 
=0.75 K. Its spin part K, which is deduced to be K
0.11 and 0.16 at respective magnetic fields H=2.0061 and 0.8671 T,. does not decrease across the superconducting transition temperature Tc for the field along the c-axis. The temperature dependence of nuclear spin-lattice relaxation of Pt below Tc has been accounted for by a Cooper pairing model with a two-component order parameter composed of spin-singlet and spin-triplet pairing components. From this result, it is shown that the Knight-shift data are consistent with the occurrence of the two-component order parameter for CePtSi.
; A Ge-NQR study under pressureHarada, Atsuyuki*; Kawasaki, Shinji*; Kotegawa, Hisashi*; Kitaoka, Yoshio*; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika; Ito, Kohei*; Haller, E. E.*; Harima, Hisatomo*
Journal of the Physical Society of Japan, 74(10), p.2675 - 2678, 2005/10
Times Cited Count：20 Percentile：68.10(Physics, Multidisciplinary)no abstracts in English
