Hait Soumyarup, Husain Sajid, Bangar Himanshu, Pandey Lalit, Barwal Vineet, Kumar Nakul, Gupta Nanhe Kumar, Mishra Vireshwar, Sharma Nikita, Gupta Pankhuri, Yadav Brajesh S, Muduli Pranaba Kishor, Chaudhary Sujeet
Thin Film Laboratory, Physics Department, Indian Institute of Technology Delhi, New Delhi 110016, India.
Spin Dynamics Laboratory, Physics Department, Indian Institute of Technology Delhi, New Delhi 110016, India.
ACS Appl Mater Interfaces. 2022 Aug 17;14(32):37182-37191. doi: 10.1021/acsami.2c09941. Epub 2022 Aug 3.
Spin pumping has been considered a powerful tool to manipulate the spin current in a ferromagnetic/nonmagnetic (FM/NM) system, where the NM part exhibits large spin-orbit coupling (SOC). In this work, the spin pumping in β-W/Interlayer (IL)/CoFeAl (CFA) heterostructures grown on Si(100 is systematically investigated with different ILs in which SOC strength ranges from weak to strong. We first measure the spin pumping through the enhancement of effective damping in CFA by varying the thickness of β-W. The damping enhancement in the bilayer of β-W/CFA (without IL) is found to be ∼50% larger than the Gilbert damping in a single CFA layer with a spin diffusion length and spin mixing conductance of 2.12 ± 0.27 nm and 13.17 ± 0.34 nm, respectively. Further, the ILs of different SOC strengths such as Al, Mg, Mo, and Ta were inserted at the β-W/CFA interface to probe their impact on damping in β-W/ILs/CFA. The effective damping reduced to 8% and 20% for Al and Mg, respectively, whereas it increased to 66% and 75% with ILs of Mo and Ta, respectively, compared to the β-W/CFA heterostructure. Thus, in the presence of ILs with weak SOC, the spin pumping at the β-W/CFA interface is suppressed, while for the high SOC ILs effective damping increased significantly from its original value of β-W/CFA bilayer using a thin IL. This is further confirmed by performing inverse spin Hall effect measurements. In summary, the transfer of spin angular momentum can be significantly enhanced by choosing a proper ultrathin interface layer. Our study provides a tool to increase the spin current production by inserting an appropriate thin interlayer which is useful in modifying the heterostructure for efficient performance in spintronics devices.
自旋泵浦被认为是在铁磁/非磁性（FM/NM）系统中操纵自旋电流的有力工具，其中非磁性部分表现出大的自旋轨道耦合（SOC）。在这项工作中，系统地研究了在Si(100)上生长的β-W/中间层（IL）/CoFeAl（CFA）异质结构中的自旋泵浦，其中使用了不同的中间层，其SOC强度范围从弱到强。我们首先通过改变β-W的厚度来测量通过增强CFA中的有效阻尼来实现的自旋泵浦。发现β-W/CFA（无中间层）双层中的阻尼增强比具有自旋扩散长度和自旋混合电导分别为2.12±0.27 nm和13.17±0.34 nm的单个CFA层中的吉尔伯特阻尼大~50%。此外，在β-W/CFA界面插入具有不同SOC强度的中间层，如Al、Mg、Mo和Ta，以探究它们对β-W/ILs/CFA中阻尼的影响。与β-W/CFA异质结构相比，Al和Mg的有效阻尼分别降至8%和20%，而Mo和Ta中间层的有效阻尼分别增加到66%和75%。因此，在存在弱SOC的中间层时，β-W/CFA界面处的自旋泵浦受到抑制，而对于高SOC中间层，使用薄中间层时有效阻尼从其β-W/CFA双层的原始值显著增加。通过进行逆自旋霍尔效应测量进一步证实了这一点。总之，通过选择合适的超薄界面层，可以显著增强自旋角动量的转移。我们的研究提供了一种通过插入合适的薄中间层来增加自旋电流产生的工具，这对于修改异质结构以在自旋电子器件中实现高效性能是有用的。
