Magnetoelectric coupling induced by exchange striction in frustrated Ising spin chain : Monte Carlo simulation

Abstract

The fascinating magnetoelectric behavior as observed in Ca₃CoMnO₆ compound [Choi et al., Phys. Rev. Lett. 100, 047601 (2008)] is investigated by using Monte Carlo simulation based on a one-dimensional elastic Ising model. The macroscopic polarization results from the ionic displacements attributed to the exchange striction in an up-up-down-down (↑↑↓↓) spin ordering. In this scenario, the microscopic structures of spin and ionic displacement are investigated at different temperatures under different external electric fields to illuminate in detail the microscopic mechanism of the strong coupling between the magnetism and the ferroelectricity. It is revealed that the change in spin configuration dependent on temperature induces the freezing and melting phenomena of the polarized domains and thus the complicated temperature-dependent ferroelectric behavior in the whole low temperature range, namely the decline of the macroscopic polarization and the broad peak of dielectric constant. On the other hand, an external electric field also has influence on the magnetic structure through affecting the ionic displacements.