Dielectric Anomaly of ZnCr₂O₄ at Antiferromagnetic Transition

抄録

Dielectric constant and magnetic susceptibility have been measured on a single crystal of ZnCr₂O₄, which is a typical example of magnetically frustrated systems. Two characteristic features are observed in the temperature dependence of dielectric constant. The first is a jump of dielectric constant at the Néel temperature, where an antiferromagnetic transition presumably of the first order occurs. The other feature is dielectric dispersion appearing below 70 K, where the presence of antiferromagnetic short-range order have been demonstrated by a neutron diffraction and a temperature dependence of magnetic susceptibility. The jump indicates the presence of the lattice distortion to relax the spin frustration which otherwise prevents magnetic long-range ordering. The origin of the dispersion is presumably related to the fluctuation of interfacial charge accompanied by magnetic fluctuation.