Giant spin torque efficiency in single-crystalline antiferromagnet Mn2Au films

Abstract

Antiferromagnetic (AFM) materials have attracted wide attention in spin-orbit torque (SOT)-based spintronic due to its abundant spin-dependent properties and unique advantage of immunity against external field perturbations. To act as the charge-to-spin conversion source in energy-saving spintronic devices, it is of great importance for the AFM material to possess a large spin torque efficiency (ξ DL). In this work, using the spin torque ferromagnetic resonance (ST-FMR) technique and a Mn 2 Au/NiFe(Py) bilayer system, we systemically study the ξ DL of AFM Mn 2 Au films with different crystal structures. Compared with polycrystalline Mn 2 Au with effective ξ DL < 0.051, we show a much larger ξ DL of~0.333 in single-crystal Mn 2 Au, which arises from the large spin Hall conductivity instead of electrical resistivity. Moreover, with a further contribution of interfacial effects, the effective ξ DL of single-crystalline Mn 2 Au/Py system increases to 0.731, which is more than two times larger than the value of~0.22 reported for the Mn 2 Au/CoFeB system. By utilizing the large ξ DL of Mn 2 Au in a perpendicularly magnetized MnGa/Mn 2 Au system, energy-efficient deterministic magnetization switching with a current density at~10 6 A cm −2 is achieved. Our results reveal a significant potential of Mn 2 Au as an efficient SOT source and shed light on its application in future AFM material-based SOT integration technology.

Temperature Dependence of Spin–Orbit Torques in Nearly Compensated Tb21Co79 Films by a Topological Insulator Sb2Te3

“…As we know, in addition to common FM layer materials, the SOT studies have also been extended to antiferromagnets (AFMs) − and ferrimagnets (FIMs) − because of their intrinsic ultrafast spin dynamics and negligible stray field . As a kind of typical FIM material, rare-earth–transition-metal (RE-TM) alloys own much stronger bulk perpendicular magnetic anisotropy (PMA) .…”

Thin Films and Devices of Evaporable Spin Crossover Complexes

“…1931 年, Cambi 等 [20] 在研究一类 Fe(III)配合物时, 发现在不同配合物中存在不同的自旋态, 之后他们还发 现某些 Fe(III)配合物的磁矩随着温度的变化而发生强烈 的变化, 这种奇特的现象意味着, 在温度变化过程中, 这些配合物中金属离子的电子构型发生了变化; 直到 30 多年后的 1964 年, Baker 等 [21] 制备了第一个具有温度 诱导自旋转变的 Fe(II)配合物: [Fe II (phen) 2 (NCS) 2 ] (phen ＝1,l0-phenanthroline), 从而开启了自旋交叉现象研究 的 新 时 期 . 这 种 现 象 通 常 主 要 发 生 在 Fe(II) [22][23][24] , Fe(III) [20] , Co(III) [25][26] 以及 Mn(III) [27][28][29] 的配合物中; 在 1989 年, Halepoto 等 [30] 报道了第一个基于 Cr(II)的具有 温度诱导自旋转变特性的配合物; 1993 年, Kröber 等 [31] 制 备 出 具 有 室 温 附 近 发 生 自 旋 转 变 的 配 合 物 分 子 [Fe II (Htz) 3 ](ClO 4 ) 2 (tz＝1,2,4-triazol-1-yl), 而且该配合物 表现出热滞后磁现象. 其后在 1994 年, Kröber 等 [32] 又制 备出了具有更高自旋转变温度(360 K)的配位聚合物体 系[Fe II (Htz) 2 (tz)](BF 4 ), 而且该分子具有很宽(≈50 K)的 热滞范围, 其接近室温的自旋转变温度以及较宽的热滞 区间, 使得其有望应用于温度响应的信息显示和开关存 储器件.…”