On the speed of piezostrain-mediated voltage-driven perpendicular magnetization reversal: a computational elastodynamics-micromagnetic phase-field study

By linking the dynamics of local piezostrain to the dynamics of local magnetization, we computationally analyzed the speed of a recently proposed scheme of piezostrain-mediated perpendicular magnetization reversal driven by a voltage pulse in magnetoelectric heterostructures. We used a model heterostructure consisting of an elliptical ultrathin amorphous Co 20 Fe 60 B 20 on top of a polycrystalline Pb(Zr,Ti)O 3 (PZT) thin film. We constructed a diagram showing the speed of perpendicular magnetization reversal as a function of the amplitude of the applied voltage pulse and the stiffness damping coefficient of PZT film. In addition, we investigated the influence of thermal fluctuations on the switching speed. The analyses suggest that the switching time remains well below 10 ns and that the energy dissipation per switching is on the order of femtojoule. The present computational analyses can be generally used to predict the speed of piezostrain-enabled magnetization switching and magnetic domain-wall motion, which critically determines the response time of corresponding piezostrain-enabled spintronic and magnonic devices. Magnetic materials: Strain quickly begins to show Mechanically controlling the magnetic properties of a material can be achieved in nanoseconds. The ability to alter the magnetic properties of a material without using a magnetic field could enable low-power electronic devices. This can be done by combining a magnetic material with a piezoelectric material – one that expands or contracts when subjected to an electric field – since the mechanical force modifies the properties of the magnetic material. Jia-Mian Hu from Pennsylvania State University and co-workers have shown that such changes can occur much faster than expected. They computationally analysed a combination of magnetic cobalt iron boron and piezoelectric lead zirconate titanate and demonstrated that such changes can occur in less than 10 nanoseconds. Their analysis will be useful for determining the response times of spintronic and magnonic devices that employ piezoelectric materials. Piezostrain-enabled magnetization switching in magnetic/piezoelectric heterostructures consists of multiple coupled kinetic processes that have rarely been considered together, thus an accurate computational analysis on the switching speed has remained outstanding. Here a computational approach is developed to accurately analyze the speed of such piezostrain-enabled magnetization switching by linkin