Metamagnetic Behavior in Heavy-Fermion Compound YbIr₂Zn₂₀

Abstract

The metamagnetic behavior in the heavy-fermion compound YbIr 2 Zn 20 with a cubic structure was studied by magnetization, de Haas–van Alphen (dHvA) oscillation, magnetoresistance, specific heat, thermal expansion, and magnetostriction measurements in single-crystalline samples. A metamagnetic anomaly at H m ≃100 kOe was found to exist in all field directions in the cubic crystal structure. The cyclotron effective mass m c * , the coefficient A in the Fermi liquid relation of electrical resistivity ρ=ρ 0 + A T 2 , and the electronic specific heat coefficient C / T indicate a peak at the metamagnetic field H m . The negative thermal expansion and negative volume magnetostriction suggest that the valence of the Yb ion gradually changes from a 4 f -itinerant state to a trivalent state with increasing magnetic field, and an almost trivalent state is realized above the metamagnetic field H m . On the other hand, the topology of the Fermi surface is approximately unchanged below and above H m in the dHvA experiment.