Fert Beijing Institute, BDBC, and School of Electronic and Information Engineering, Beihang University, 100191, Beijing, China.
Singulus Technologies, 63796, Kahl am Main, Germany.
Nat Commun. 2018 Feb 14;9(1):671. doi: 10.1038/s41467-018-03140-z.
Perpendicular magnetic tunnel junctions based on MgO/CoFeB structures are of particular interest for magnetic random-access memories because of their excellent thermal stability, scaling potential, and power dissipation. However, the major challenge of current-induced switching in the nanopillars with both a large tunnel magnetoresistance ratio and a low junction resistance is still to be met. Here, we report spin transfer torque switching in nano-scale perpendicular magnetic tunnel junctions with a magnetoresistance ratio up to 249% and a resistance area product as low as 7.0 Ω µm, which consists of atom-thick W layers and double MgO/CoFeB interfaces. The efficient resonant tunnelling transmission induced by the atom-thick W layers could contribute to the larger magnetoresistance ratio than conventional structures with Ta layers, in addition to the robustness of W layers against high-temperature diffusion during annealing. The critical switching current density could be lower than 3.0 MA cm for devices with a 45-nm radius.
基于 MgO/CoFeB 结构的垂直磁隧道结因其优异的热稳定性、缩放潜力和功耗而成为磁随机存取存储器的研究热点。然而，目前在具有较大隧道磁电阻比和较低结电阻的纳米柱中实现电流诱导开关仍然是一个挑战。在这里，我们报道了具有高达 249%的磁电阻比和低至 7.0 Ωµm 的电阻-面积乘积的纳米级垂直磁隧道结中的自旋转移扭矩开关，该磁隧道结由原子层厚的 W 层和双层 MgO/CoFeB 界面组成。原子层厚的 W 层引起的高效共振隧穿传输有助于获得比传统 Ta 层结构更大的磁电阻比，此外，W 层在退火过程中对高温扩散具有较强的稳定性。对于半径为 45nm 的器件，临界开关电流密度可能低于 3.0 MA/cm。
