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

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3 Citations (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.

Original languageEnglish
Pages (from-to)74-77
Number of pages4
Journaljournal of the physical society of japan
Issue numberSUPPL. A
Publication statusPublished - 2007
Externally publishedYes


  • Heavy-fermion compound
  • Pressure
  • Specific heat
  • YbAgGe
  • YbRhSb

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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