Metamagnetic Behavior and Effect of Pressure on the Electronic State in Heavy-Fermion Compound YbRh

概要

論文の詳細を見る
We measured the magnetic susceptibility, high-field magnetization, magnetoresistance, specific heat, and Hall coefficient, together with the electrical resistivity under high pressures and magnetic fields, for the heavy-fermion compound YbRh<inf>2</inf>Zn<inf>20</inf>with the cubic CeCr<inf>2</inf>Al<inf>20</inf>-type structure. The metamagnetic behavior was observed at H_{\text{m}} = 65 kOe for the magnetic field along the \langle 100\rangle direction below T_{\chi_{\text{max}}} = 5.3 K, at which the temperature of the magnetic susceptibility indicates a broad maximum. The coefficient A of the T^{2} dependence of electrical resistivity \rho=\rho_{0} + AT^{2} and the electronic specific heat coefficient C/T possess a broad maximum at H_{\text{m}}. The metamagnetic field H_{\text{m}} is found to decrease with increasing pressure and to become zero at a critical pressure P_{\text{c}} \simeq 5.2 GPa. Correspondingly, the A value increases drastically in magnitude, and the Fermi liquid relation is no longer satisfied at 5.2 GPa in zero magnetic field, implying a non-Fermi liquid state. On the other hand, at magnetic fields of H > 20 kOe, the low-temperature resistivity exhibits a T^{2} dependence even at 5.2 GPa. The A coefficient decreases rapidly with increasing magnetic field. These results indicate that an electronic state at 5.2 GPa corresponds to the quantum critical point.
2013-08-15