Fieldlike spin-orbit torque in ultrathin polycrystalline FeMn films
Fieldlike spin-orbit torque in ultrathin polycrystalline FeMn films
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DOI：
10.1103/physrevb.93.094402
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发表时间：
2016-03
影响因子：
3.7
通讯作者：
Yumeng Yang;Yanjun Xu;Xiaoshan Zhang;Ying Wang;Shufeng Zhang;Run‐Wei Li;Meysam Sharifzadeh Mirshekarloo;K. Yao;Yihong Wu
中科院分区：
文献类型：
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作者：
Yumeng Yang;Yanjun Xu;Xiaoshan Zhang;Ying Wang;Shufeng Zhang;Run‐Wei Li;Meysam Sharifzadeh Mirshekarloo;K. Yao;Yihong Wu
用平面霍尔效应测量了超薄多晶FeMn/Pt双层膜中的类场自旋轨道矩。FeMn在2 ~ 5 nm的厚度范围内获得了较大的有效场。实验观测结果可以合理地解释下，FeMn层是由两个自旋亚晶格具有不相等的磁化强度的假设下，使用宏观自旋模型。考虑到FeMn中的未补偿净矩比NiFe小得多，大的有效场证实了有效场的自旋霍尔起源。NiFe/FeMn/Pt三层膜中Pt产生的自旋电流仅能穿过1 ~ 4 nm厚的FeMn层，这进一步证实了FeMn对自旋电流的有效吸收。通过量化NiFe中诱导的类场有效场，估计FeMn中的自旋扩散长度为2 nm，与文献中通过铁磁共振和自旋泵浦实验报道的值一致。
Field-like spin orbit torque in FeMn/Pt bilayers with ultra-thin polycrystalline FeMn has been characterized through planar Hall effect measurements. A large effective field is obtained for FeMn in the thickness range of 2 to 5 nm. The experimental observations can be reasonably accounted for by using a macro-spin model under the assumption that the FeMn layer is composed of two spin sublattices with unequal magnetizations. The large effective field corroborates the spin Hall origin of the effective field considering the much smaller uncompensated net moments in FeMn as compared to NiFe. The effective absorption of spin current by FeMn is further confirmed by the fact that spin current generated by Pt in NiFe/FeMn/Pt trilayers can only travel through the FeMn layer with a thickness of 1 to 4 nm. By quantifying the field-like effective field induced in NiFe, a spin diffusion length of 2 nm is estimated in FeMn, in consistence with values reported in literature by ferromagnetic resonance and spin-pumping experiments.