Theory for toggle magnetic random access memory: The asymmetric case

A single domain model is used to analyze the magnetic switching of two coupled magnetic layers, relevant for toggle magnetic random access memory, for the nonideal case where the layers are not identical. In general, we show that discontinuous transitions occur across the critical switching curve and continuous transitions occur around cusps in the critical switching curve. We illustrate this with examples of thickness imbalance, anisotropy mismatch, and Neel coupling and derive the corresponding switching behavior. Features in the direct- write switching can be used to experimentally distinguish between these various sources of asymmetry. (C)2007 American Institute of Physics.