180°180° magnetization switching in nanocylinders by a mechanical strain

The magnetization switching dynamics in ferromagnetic Cobalt nanocylinders under mechanical loading is studied by a constraint-free phase field model, which allows the exactly constant magnetization magnitude and the explicit magneto-mechanical coupling. Results show that the single-domain switching mode, which is of great interest for memory technologies, exists only in small nanocylinders, and the critical radius is found to be around 8 nm. Furthermore, a novel mechanical loading and unloading scheme, which makes use of the overrun of magnetization during the precessional switching, is proposed to achieve a deterministic 180°180° switching. The 180°180° switching is driven firstly by the magneto-mechanical coupling and then by the magnetocrystalline anisotropy (KuKu). The threshold strain to induce the deterministic switching increases with KuKu. The switching time firstly decreases with increasing strain rapidly and then saturates. The results shed light on the design of an optimum mechanically driven nanomagnets-based logic and memory devices.