Strain induced and spin torque induced switching of nanomagnets: Coherent or incoherent?

We have studied magnetization switching in elliptical multiferroic nanomagnets due to strain and in other elliptical nanomagnets due to spin torque generated via the spin Hall effect. These switching mechanisms were chosen since they promise to be the two most energy-efficient strategies for switching nanomagnets. Micromagnetic simulations showed that strain induced switching is coherent in small nanomagnets but incoherent in larger ones, while the spin torque induced switching is always incoherent, in even small nanomagnets. This has implications for nanomagnetic logic and memory.