Eur. Phys. J. B (2015) 88: 328
https://doi.org/10.1140/epjb/e2015-60649-4

Regular Article

Theory of magnetic field control on polarization in multiferroic RCrO₃ compounds

¹ University of Architecture, Civil Engineering and Geodesy, Faculty of Hydrotechnics, Hr. Smirnenski Blvd. 1, 1046 Sofia, Bulgaria
² University of Forestry, Faculty of Forest Industry, Kl. Ohridsky Blvd. 10, 1756 Sofia, Bulgaria
³ University of Sofia, Department of Physics, J. Bouchier Blvd. 5, 1164 Sofia, Bulgaria

^a e-mail: julia@phys.uni-sofia.bg

Received: 7 August 2015
Received in final form: 24 September 2015
Published online: 9 December 2015

Abstract

A microscopic mechanism to describe the magnetic field H dependence of the polarization P is proposed on the basis of a microscopic model for RCrO₃ including the spin-phonon interaction. Using the Green’s function theory in Peierls systems we have studied the two contributions to P due to the antisymmetric exchange Dzyaloshinskii-Moriya interaction P_AS and the magnetostriction P_MS. The behaviour of P(H) – increase or decrease – in different multiferroics can be explained in our model taking into account the second order spin-phonon interaction constants. When a magnetic field is applied to a magnetoelectric material, the material is strained. H changes the average of the spin operator products and so P. Moreover, H renormalizes the elastic constant which explains the strain effect. From here we have found a qualitative relationship between pressure and magnetic field effects on P. The observed results are in good qualitatively agreement with the experimental data.