広瀬 雄介*; 三浦 泰直*; 堤 泰樹*; 吉内 伸吾*; 大家 政洋*; 杉山 清寛*; 竹内 徹也*; 山上 浩志*; 山本 悦嗣; 芳賀 芳範; et al.
Physica Status Solidi (B), 250(3), p.642 - 645, 2013/03
Electronic states of an antiferromagnet UCd and its reference compound ThCd were investigated by means of de Haas-van Alphen (dHvA) effect. From the cyclotron effective mass determined from the dHvA oscillation, the electronic specific heat of UCd was estimated as 100 mJ/Kmol, much smaller than 840 in the previous report. The result suggests that magnetic excitation contributes significantly to the specific heat.
大貫 惇睦; 安井 慎一*; 松下 昌輝*; 吉内 伸吾*; 大家 政洋*; 広瀬 雄介*; Dung, N. D.*; 本多 史憲*; 竹内 徹也*; 摂待 力生*; et al.
Journal of the Physical Society of Japan, 80(Suppl.A), p.SA003_1 - SA003_6, 2011/12
We studied the Fermi surface properties of YbCuSi and YbCuGe with the tetragonal structure by measuring the de Haas-van Alphen (dHvA) oscillations, together with the energy band calculations. It was clarified that 4f electrons contribute to the Fermi surface of a valence fluctuating compound YbCuSi, but not to that of a divalent compound YbCuGe. We also studied the heavy fermion properties of YbTZn (T: Co, Rh, Ir) with the cubic caged structure. The metamagnetic behavior or an abrupt nonlinear increase of magnetization was observed. By measuring the electrical resistivity under pressure and magnetic field, we clarified that the electronic state close to the quantum critical point is realized in YbIrZn at 5.2 GPa and also YbCoZn at ambient pressure.
大貫 惇睦; 安井 慎一*; 吉内 伸吾*; 大家 政洋*; 松下 昌輝*; 広瀬 雄介*; 竹内 徹也*; 本多 史憲*; 摂待 力生*; 杉山 清寛*; et al.
Journal of Physics; Conference Series, 273, p.012013_1 - 012013_4, 2011/02
Metamagnetic behavior of the heavy fermion compound YbIrZn has been studied experimentally. The metamagnetic transition was clearly seen in the bulk magnetization curve. Near the metamagnetic critical field H 100 kOe, the effective mass of conduction electrons exhibits a significant enhancements. It is suggested that the present metamagnetism is related to the magnetic instability around the quantum critical point.
竹内 徹也*; 安井 慎一*; 戸田 雅敏*; 松下 昌輝*; 吉内 伸吾*; 大家 政洋*; 片山 敬亮*; 広瀬 雄介*; 吉谷 尚久*; 本多 史憲*; et al.
Journal of the Physical Society of Japan, 79(6), p.064609_1 - 064609_15, 2010/06
Metamagnetic behavior of the heavy-fermion compound YbIrZn was studied by magnetization, de Haas-van Alphen effect, magnetoresistance, specific heat, thermal expansion and magnetostriction. Metamagnetic behavior was observed for all the physical properties at low temperatures. It is remarkable that the Fermi surfaces observed in the dHvA effect unchanges across the metamagnetic transition.
吉内 伸吾*; 竹内 徹也*; 大家 政洋*; 片山 敬亮*; 松下 昌輝*; 吉谷 尚久*; 西村 尚人*; 太田 尚志*; 立岩 尚之; 山本 悦嗣; et al.
Journal of the Physical Society of Japan, 79(4), p.044601_1 - 044601_11, 2010/04
We succeeded in growing single crystals of cage-structure compounds RCd (R: La, Ce, and Pr) and precisely studied their low-temperature magnetic and electronic properties. We found antiferromagnetic ordering at 0.44 and 0.39 K in CeCd and PrCd, respectively, and clarified the magnetic phase diagrams of the compounds. From the dHvA experiment, we detected small dHvA branches ranging from 710 to 210 Oe, which correspond to small Fermi surfaces. This is mainly due to a small Brillouin zone based on a large unit cell. Moreover, the dHvA frequencies and cyclotron masses are approximately the same among RCd, revealing a localized character of 4f electrons in CeCd and PrCd.
吉内 伸吾*; 戸田 雅敏*; 松下 昌輝*; 安井 慎一*; 広瀬 雄介*; 大家 政洋*; 片山 敬亮*; 本多 史憲*; 杉山 清寛*; 萩原 政幸*; et al.
Journal of the Physical Society of Japan, 78(12), p.123711_1 - 123711_4, 2009/12
High-field magnetization and de Haas-van Alphen effect were measured on a heavy fermion compound YbIrZn. Large cyclotron masses ranging from 4 to 27 were detected in the dHvA experiment, and are found to be reduced at magnetic fields higher than 120 kOe. From the present experimental results together with the 4f-itinerant band calculations, the 4f electrons are considered to form heavy fermion state.