Giant magnetocapacitance in cerium sesquioxide

Abstract

We report structural, magnetic, magnetodielectric, and specific heat properties of hexagonal polymorph of Ce2O3. The A-type hexagonal Ce2O3 crystallizes in the P32/m1 space group and shows antiferromagnetic ordering at TN≈6.2 K as detected by magnetic susceptibility measurements. The magnetic ordering is accompanied by a λ-shape specific heat anomaly with a peak maximum at T≈6.1 K. An isotropic dielectric constant demonstrates a large magnetocapacitance effect at T=TN, which saturates at ∼80 kOe. In the magnetically ordered phase the relaxation rate of the dielectric polarization increases with the magnetic field and shows divergence as the temperature approaches TN. The magnetic calculations indicate that Ce2O3 undergoes "easy plane" AFM ordering, which is also supported by the neutron diffraction data.