Reversible Control of Magnetic Interactions by Electric Field in a Single Phase Material

Intrinsic magnetoelectric coupling describes the interaction between magnetic and electric polarization through an inherent microscopic mechanism in a single phase material. This phenomenon has the potential to control the magnetic state of a material with an electric field, an enticing prospect for device engineering. We demonstrate 'giant' magnetoelectric cross-field control in a single phase rare earth titanate film. In bulk form, EuTiO3 is antiferromagnetic. However, both anti and ferromagnetic interactions coexist between different nearest neighbor europium ions. In thin epitaxial films, strain can be used to alter the relative strength of the magnetic exchange constants. Here, we not only show that moderate biaxial compression precipitates local magnetic competition, but also demonstrate that the application of an electric field at this strain state, switches the magnetic ground state. Using first principles density functional theory, we resolve the underlying microscopic mechanism resulting in the EuTiO3 G-type magnetic structure and illustrate how it is responsible for the 'giant' cross-field magnetoelectric effect

Influence of pressure on the structural, dynamical, and electronic properties of the SnP2S6 layered crystal

International audienceUsing the density functional theory in the local density approximation the pressure dependence of the structural, dynamical, and electronic properties of the SnP2S6 layered semiconductor in the pressure range up to 35 GPa is investigated. The pressure dependence of the lattice parameters is well described by the Murnaghan equation of state. The nonmonotonic pressure dependence of the structural polarization is obtained. The SnP2S6 compound is predicted to be an indirect-gap semiconductor. At a pressure of above 10 GPa, an indirect-direct bandgap crossover is observed. The pressure dependence of the long-wavelength lattice vibration frequencies is calculated and compared with experimental results from Raman spectroscopy in the pressure range 0–21.5 GPa. Full phonon dispersion curves do not indicate mode softening over the entire range of the Brillouin zone. The stability of the structure under pressure is discussed