Mechanically induced deterministic 180° switching in nanomagnets

•A constraint-free phase model is used for magneto-mechanically coupled nanomagnets.•Mechanically induced magnetization switching dynamics is readily captured.•Size dependence of mechanically induced switching mode is identified.•Mechanically driven/assisted 180° switching of nanomagnets is indeed feasible.•180° switching under combined mechanical loading and magnetic field is explored.

The mechanically induced magnetization switching in nanomagnets is studied by a constraint-free phase field model, which permits exactly constant magnetization magnitude and explicit magneto-mechanical coupling. Depending on the geometry of the nanomagnets, there exist two distinct switching modes: one is the coherent mode where the magnetization vector remains homogeneous during the switching, and the other is the incoherent mode where heterogeneous magnetization distribution occurs. For the application of nanomagnets-based logic and memory devices, the coherent mode is of great interest. Results show that a deterministic 180° switching can happen if mechanical loading is removed once the magnetization rotates to the largest switching angle. The switching time decreases with the magnitude of the applied strain. In addition, the 180° switching under a combination of magnetic field and mechanical strain is also investigated. Simulations demonstrate that an optimum additional strain to reduce the switching time is around 0.2%. The mechanically induced switching is further shown to be damping dependent. A larger damping coefficient is favorable for a faster switching only when the deterministic 180° switching can be guaranteed. This work provides a foundation for the study of mechanically driven/assisted nanomagnets-based logic and memory devices.

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