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青木 大*; Taupin, M.*; Paulsen, C.*; Hardy, F.*; Taufour, V.*; 小手川 恒*; Hassinger, E.*; Malone, L.*; 松田 達磨; 三宅 厚志*; et al.
Journal of the Physical Society of Japan, 81(Suppl.B), p.SB002_1 - SB002_6, 2012/12
被引用回数:3 パーセンタイル:26.68(Physics, Multidisciplinary)We review our recent studies on ferromagnetic superconductors, UGe2, URhGe, and UCoGe. We focus on experimental results of URhGe and UCoGe in which the superconductivity occurs already at ambient pressure. The huge upper critical field on UCoGe for the field along the hard magnetization axis (-axis) is confirmed by the AC susceptibility measurements by the fine tuning of field angle. Contrary to the huge along the hard-magnetization axis, along the easy-magnetization axis (-axis) is relatively small in value. However, the initial slope of , namely / (0) both in UCoGe and in URhGe indicates the large value, which can be explained by the magnetic domain effect detected in the magnetization measurements. The specific heat measurements using a high quality single crystal of UCoGe demonstrate the bulk superconductivity, which is extended under magnetic field for the field along -axis.
青木 大*; Paulsen, C.*; 松田 達磨; Malone, L.*; Knebel, G.*; Haen, P.*; Lejay, P.*; 摂待 力生*; 大貫 惇睦; Flouquet, J.*
Journal of the Physical Society of Japan, 80(5), p.053702_1 - 053702_4, 2011/05
被引用回数:17 パーセンタイル:68.02(Physics, Multidisciplinary)Resistivity measurements performed under pressure in the paramagnetic ground state of CeRuSi are reported. They demonstrate that the relative change of effective mass through the pseudo metamagnetic transition is invariant under pressure. The results are compared with the first order metamagnetic transition due to the antiferromagnetism of CeLaRuSi which corresponds to the "negative" pressure of CeRuSi by volume expansion. Finally, we describe the link between the spin-depairing of quasiparticles on CeRuSi and that of Cooper pairs on the unconventional heavy fermion superconductor CeCoIn.
Flouquet, J.*; 青木 大*; Bourdarot, F.*; Hardy, F.*; Hassinger, E.*; Knebel, G.*; 松田 達磨; Maingast, C.*; Paulsen, C.*; Taufour, V.*
Journal of Physics; Conference Series, 273, p.012001_1 - 012001_25, 2011/02
被引用回数:15 パーセンタイル:95.16(Physics, Condensed Matter)A brief review on major advances in heavy fermion physics is presented including the Ce metal phase diagram, the huge effective mass detected in CeAl, and the successive discoveries of unconventional superconductivity in CeCuSi and three U based compounds, UBe, UPt and URuSi. In order to track the origin of the huge effective mass, the case of intermediate valence compounds is discussed with emphasis on the differences between Yb and Ce materials. Pressure and magnetic-field studies on the ferromagnetic superconductor URhGe illustrate the role of the singular effective mass enhancement on the superconducting pairing.