Dielectric properties of multiferroic CuCrO2

摘要

We propose a microscopic model in order to study the multiferroic properties of the triangular compound CuCrO2 taking into account antiferromagnetic interactions in the ab plane, spin-phonon interactions and quadratic magnetoelectric (ME) coupling. The temperature and magnetic field dependence of the polarization Pab and dielectric constant epsilon(ab) is calculated. P-ab increases when h is parallel to its direction and decreases when h is perpendicular to it. We show that epsilon(ab) has a kink near the magnetic phase transition T-N = 24 K which disappears with increasing of an external magnetic field h(ab). This behavior is an evidence for a strong ME coupling and in qualitative agreement with the experimental data.