Reduced Exchange Interactions in Magnetic Tunnel Junction Free Layers with Insertion Layers
arXiv:1905.09329 · doi:10.1021/acsaelm.9b00381
Abstract
Perpendicularly magnetized CoFeB layers with ultra-thin non-magnetic insertion layers are very widely used as the electrodes in magnetic tunnel junctions for spin transfer magnetic random access memory devices. Exchange interactions play a critical role in determining the thermal stability of magnetic states in such devices and their spin torque switching efficiency. Here the exchange constant of free layers incorporated in full magnetic tunnel junction layer stacks, specifically CoFeB free layers with W insertion layers is determined by magnetization measurements in a broad temperature range. A significant finding is that the exchange constant decreases significantly and abruptly with W insertion layer thickness. The perpendicular magnetic anisotropy shows the opposite trend; it initially increases with W insertion layer thickness and shows a broad maximum for approximately one monolayer (0.3 nm) of W. These results highlight the interdependencies of magnetic characteristics required to optimize the performance of magnetic tunnel junction devices.
arXiv commentsubmitted to Advanced Electronic Materials
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- Thermal effects in spin torque switching of perpendicular magnetic tunnel junctions at cryogenic temperatures
- Key points in the determination of the interfacial Dzyaloshinskii-Moriya interaction from asymmetric bubble domain expansion
- Spin-torque switching mechanisms of perpendicular magnetic tunnel junctions nanopillars
- Micromagnetic instabilities in spin-transfer switching of perpendicular magnetic tunnel junctions
- Beyond conventional skyrmions in synthetic antiferromagnets