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

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 ${H}_{c}\ensuremath{\sim}4$ kOe. In the $H\ensuremath{-}T$ 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 ${H}_{c}\ensuremath{\sim}4$ kOe; (II) field-induced anomalous state in which the electrical resistivity follows $\ensuremath{\Delta}\ensuremath{\rho}(T)\ensuremath{\propto}{T}^{1.5}$ between ${H}_{c}$ and $\ensuremath{\sim}$8 kOe; and (III) Fermi liquid (FL) state in which $\ensuremath{\Delta}\ensuremath{\rho}(T)\ensuremath{\propto}{T}^{2}$ for $H\ensuremath{\ge}8$ 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 4$f$ states of Yb, region II may be a manifestation of a spin liquid state.