Anomalous anti-damping in sputtered β-Ta/Py bilayer system.
Anomalous anti-damping in sputtered β-Ta/Py bilayer system.
复制标题
溅射的β-TA/PY双层系统中的异常抗阻尼。
DOI：
10.1038/srep19488
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发表时间：
2016-01-19
影响因子：
4.6
通讯作者：
Pandya DK
中科院分区：
文献类型：
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作者：
Behera N;Chaudhary S;Pandya DK
在溅射Ni_（81）Fe_（19）（Py）薄膜中，当与很薄的β-Ta层接触时，有效阻尼参数α_（eff）反常地降低，而不需要直流电流。这种αeff的降低，也被称为反阻尼效应，被发现与β-Ta层的厚度密切相关; αeff最高，即，裸Ni 81 Fe 19（18 nm）/SiO2/Si的最小值为0.0093 ± 0.0003，而β-Ta（6 nm）/Py（18 nm）/SiO2/Si的最小值为0.0077 ± 0.0001。这种反常的反阻尼效应可以从界面Rashba效应和自旋泵激引起的Ta/Py界面附近β-Ta层中的非平衡扩散自旋累积效应两个方面来理解，界面Rashba效应与薄的保护性Ta 2 O 5势垒层的形成有关，自旋泵激引起的非平衡扩散自旋累积效应在Py中的磁矩上引起额外的自旋轨道力矩（SOT），导致（tTa）的拟合揭示了界面自旋混合电导和自旋扩散长度的反常负性。在tTa = 6 nm以上观察到的αeff的增加归因于在较高tTa下SOT的减弱。该研究突出了使用β-Ta基纳米结构在开发具有可调谐以及低α值的低功率自旋电子器件中的潜力。
Anomalous decrease in effective damping parameter αeff in sputtered Ni81Fe19 (Py) thin films in contact with a very thin β-Ta layer without necessitating the flow of DC-current is observed. This reduction in αeff, which is also referred to as anti-damping effect, is found to be critically dependent on the thickness of β-Ta layer; αeff being highest, i.e., 0.0093 ± 0.0003 for bare Ni81Fe19(18 nm)/SiO2/Si compared to the smallest value of 0.0077 ± 0.0001 for β-Ta(6 nm)/Py(18 nm)/SiO2/Si. This anomalous anti-damping effect is understood in terms of interfacial Rashba effect associated with the formation of a thin protective Ta2O5 barrier layer and also the spin pumping induced non-equilibrium diffusive spin-accumulation effect in β-Ta layer near the Ta/Py interface which induces additional spin orbit torque (SOT) on the moments in Py leading to reduction in . The fitting of (tTa) revealed an anomalous negative interfacial spin mixing conductance, and spin diffusion length,. The increase in αeff observed above tTa = 6 nm is attributed to the weakening of SOT at higher tTa. The study highlights the potential of employing β-Ta based nanostructures in developing low power spintronic devices having tunable as well as low value of α.