One-dimensional short-range magnetic correlations in the magnetoelectric pyroxene CaMnGe2 O6

Abstract

We have investigated the magnetic and magnetoelectric properties of CaMnGe2O6 by means of powder neutron diffraction, magnetic susceptibility, heat capacity, and electrical polarization measurements. The presence of one-dimensional short-range magnetic correlations within the MnO6 octahedra chains well above long-range antiferromagnetic ordering (15 K) was evidenced. A one-dimensional antiferromagnetic correlation model along the zigzag chains was developed to fit the diffuse magnetic scattering. The linear magnetoelectric effect and pertinent ferrotoroidicity, allowed by the magnetic symmetry (C2′/c), have been verified experimentally and theoretically.