Multiferroic materials for spin-based logic devices

Logical devices based on spin waves offer the potential to avoid dissipation mechanisms that limit devices based on either the charge or spin of mobile electrons. Multiferroic magnetoelectrics, which are materials that combine ferroelectric and magnetic order, allow direct switching of magnetic order and thence of spin-wave properties using an applied electric field. The intrinsic coupling between polarization and magnetic moments, generated by strong electronic correlations in these multiferroic materials, is argued to provide new approaches to spin-wave injection and spin-wave switching using applied voltages with no external magnetic field. These effects are shown to arise in a phenomenological Landau theory of coupled electronic and magnetic orders in multiferroic BiFeO3, and found to depend subtly on differences between the crystalline and film states of this material.