Magnetic-field-tuned quantum criticality of the heavy-fermion system YbPtBi

摘要

In this paper, we present systematic measurements of the temperature and magnetic field dependencies of the thermodynamic and transport properties of the Yb-based heavy fermion YbPtBi for temperatures down to 0.02 K with magnetic fields up to 140 kOe to address the possible existence of a field-tuned quantum critical point. Measurements of magnetic-field- and temperature-dependent resistivity, specific heat, thermal expansion, Hall effect, and thermoelectric power indicate that the AFM order can be suppressed by an applied magnetic field of H_c～ 4 kOe. In the H-T phase diagram of YbPtBi, three regimes of its low-temperature states emerge: (Ⅰ) AFM state, characterized by a spin density wave-like feature, which can be suppressed to T = 0 by the relatively small magnetic field of H_c～ 4 kOe; (Ⅱ) field-induced anomalous state in which the electrical resistivity follows △ρ(T) between T~1.5 between H_c and ～8 kOe; and (Ⅲ) Fermi liquid (FL) state in which △ρ(T) oc T~2 for H≥8 kOe. Regions Ⅰ and Ⅱ are separated at T = 0 by what appears to be a quantum critical point. Whereas region Ⅲ appears to be a FL associated with the hybridized 4f states of Yb, region Ⅱ may be a manifestation of a spin liquid state.