Proposal of a Multistate Memory Using Voltage Controlled Magnetic Anisotropy of a Cross-Shaped Ferromagnet

Voltage controlled magnetic anisotropy (VCMA)-induced precessional magnetization dynamics of a cross-shaped ferromagnet (FM) is studied by micromagnetic simulation. A cross-shaped FM, which has four minima in its energy landscape, can be used to store two bits. We show that, by selecting appropriate dimensions and taking into account interfacial perpendicular magnetic anisotropy, the cross-shaped FM can be switched from one state to the other states using VCMA, while the in-plane component of magnetization provides multistate functionality. VCMA-induced switching provides a low-power alternative to spin-transfer-torque switching of a similar cross-shaped FM studied previously. We estimate the thermal stability using the string method to capture the complex micromagnetic nature of the switching along the minimum energy path. The results could be useful toward development of a low-power multistate nonvolatile memory.