Shape-anisotropy magnetic tunnel junction (MTJ) is a promising candidate for spin-transfer torquemagnetoresistive random access memory (STT-MRAM) at 1X- and X-nm generations. Conventionalinterfacial-anisotropy MTJ with a CoFeB/MgO structure allows to reduce the MTJ size down to 20 nmwhile keeping high thermal stability factor Δ; however, further scaling beyond 20 nm is challenging dueto an insufficient anisotropy energy density. Recently, high Δ at such small region was shown to beachieved utilizing shape anisotropy of a cylindrical MTJ. From both fundamental and application pointsof view, it’s important to study energy barrier E for shape-anisotropy MTJ at elevated temperatures. In thisstudy, we measure temperature dependence of of the shape- and interfacial-anisotropy MTJs below 1Xnm in order to understand the mechanism of variation in E with temperature for the two types of MTJs.
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