Temperature dependence of the energy barrier in X/1X nm shape-anisotropy magnetic tunnel junctions

摘要

Shape-anisotropy magnetic tunnel junctions (MTJs) are attracting much attention as a high-performance nonvolatile spintronic device in the X/1X nm regime. In this study, we investigate an energy barrier relevant to the retention property in CoFeB/MgO-based shape-anisotropy MTJs with various diameters at high temperatures and compare it with that in conventional interfacial-anisotropy MTJs. We find that the scaling relationship between the energy barrier and the spontaneous magnetization in shape-anisotropy MTJs is well described by a model assuming the dominant contribution of shape anisotropy to the energy barrier. Also, the scaling exponent is much smaller than that for the interfacial-anisotropy MTJs, indicating that the properties of shape-anisotropy MTJs are less sensitive to the temperature. Using the experimentally determined scaling relationship, we discuss the design window of the MTJ dimensions to achieve data retention of 10 years at various temperatures. This study demonstrates that the shape-anisotropy MTJ holds promise of scaling beyond 20 nm for high-temperature applications.