Pressure-induced magnetic phase transitions in Yb-based heavy-fermion compounds

Kazunori Umeo, Hirokazu Kubo, Fumihiko Nakamura, Yukio Haizaki, Kenichi Katoh, Akira Ochiai, Toshiro Takabatake

研究成果: Article査読

3 被引用数 (Scopus)


We report a detailed study of the pressure (P)-temperature (T) phase diagrams of two Yb-based heavy-fermion compounds, namely, the antiferromagnet YbAgGe and weak ferromagnet YbRhSb. YbAgGe with a quasikagome lattice of Yb ions undergoes two magnetic phase transitions at TM1=0.8 K (second order) and TM2=0.65 K (first order). With increasing pressure (P) up to 0.5 GPa, the transitions at TM1 and TM2 merge into one transition. For 0.5 < P < 1.6 GPa, TM2 remains constant and abruptly rises above 1.6 GPa. This rise occurs with a significant change in the specific heat anomaly from a small cusp at TM2 into a large peak at TM3. This finding suggests that the suppressed magnetic entropy is released due to geometrical frustration at ambient pressure. On the other hand, YbRhSb undergoes a transition into an unusual magnetic state at T M1=2.7 K, which is associated with a small spontaneous moment of 3 x 10-3 /μB/Yb. Measurements of the resistivity, specific heat, and ac magnetic susceptibility χac reveal that the application of pressure above 0.9 GPa induces another magnetic transition at TM2 below TM1. TM2(P) exhibits a V-shaped minimum of 1.8 K at PC=1.6 GPa. With increasing pressure up to 2 GPa, the significant enhancement of the peak height of χac suggests that the canted antiferromagnetic state below PC changes to a ferromagnetic state with a large magnetic moment above PC. These complex P-T phase diagrams for YbAgGe and YbRhSb are explained in terms of the competition among distinct types of magnetic interactions, magnetic frustration, and crystal field anisotropy.

ジャーナルjournal of the physical society of japan
出版ステータスPublished - 2007 1月 1

ASJC Scopus subject areas

  • 物理学および天文学(全般)


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