Material strategies for energy-efficient voltage-controlled magnetic tunnel junctions

Abstract The realization of spin manipulation using electric fields is anticipated to be a promising route toward future spintronic devices with ultra-low driving power as well as zero standby power, such as voltage-controlled (VC)—magnetoresistive random access memory (MRAM). Among various methods, the VC magnetic anisotropy (VCMA) effect in magnetic tunnel junctions (MTJs) is regarded as a particularly effective approach for achieving electric-field-induced magnetization control. One of the most important technical challenges in VC-MRAM development is to achieve a large VCMA coefficient, which is essential for ensuring scalability and reliable information writing. This review discusses the fundamental aspects of the VCMA effect and outlines recent attempts to optimize material and device structures to improve the VCMA coefficient in both epitaxial and polycrystalline MTJs.