An Suhyeok, Baek Eunchong, Kim Jin-A, Lee Ki-Seung, You Chun-Yeol
Department of Emerging Materials Science, DGIST, Daegu, 42988, Korea.
Emerging Materials Science Research Center, DGIST, Daegu, 42988, Korea.
Sci Rep. 2022 Mar 2;12(1):3465. doi: 10.1038/s41598-022-06960-8.
Increasing the efficiency of spin-orbit torque (SOT) is of great interest in spintronics devices because of its application to the non-volatile magnetic random access memory and in-logic memory devices. Accordingly, there are several studies to alter the magnetic properties and reduce the SOT switching current with helium ion irradiation, but previous researches are focused on its phenomenological changes only. Here, the authors observe the reduction of switching current and analyze its origins. The analyzed major reasons are improved spin Hall angle represented as the changed resistivity of heavy metal layer and the reduction of surface anisotropy energy at interface between heavy metal and ferromagnet. It is confirmed that almost linear relation between changed SHA and Pt resistivity by helium ion irradiation, which is attributed because of the increase in the scattering sources induced by structural distortion during ion penetration. From the calculated power consumption ratio based on the derived parameter, the requiring power decreases according to the degree of ion irradiation. Our results show that helium ion penetration induced layer and interfacial disturbance affects SOT induced magnetization switching current reduction and may provide possibility about helium ion irradiation based superior SOT device engineering.
提高自旋轨道扭矩（SOT）的效率在自旋电子器件中备受关注，因为它可应用于非易失性磁性随机存取存储器和逻辑内存储器器件。因此，有多项研究通过氦离子辐照来改变磁性能并降低SOT开关电流，但以往的研究仅关注其现象学变化。在此，作者观察到开关电流的降低并分析了其根源。分析的主要原因是自旋霍尔角的改善，表现为重金属层电阻率的变化，以及重金属与铁磁体界面处表面各向异性能量的降低。证实了氦离子辐照引起的自旋霍尔角变化与铂电阻率之间几乎呈线性关系，这归因于离子穿透过程中结构畸变导致散射源增加。根据推导参数计算出的功耗比表明，所需功率随离子辐照程度降低。我们的结果表明，氦离子穿透引起的层和界面扰动会影响SOT诱导的磁化翻转电流降低，并可能为基于氦离子辐照的高性能SOT器件工程提供可能性。
