Zhang Xiaolin, Yang Baishun, Guo Xiaoyan, Han Xiufeng, Yan Yu
Key Laboratory of Physics and Technology for Advanced Batteries (Ministry of Education), Department of Physics, Jilin University, Changchun 130012, China.
Shenzhen JL Computational Science and Applied Research Institute, Shenzhen 518109, China.
Nanoscale. 2021 Dec 13;13(47):19993-20001. doi: 10.1039/d1nr04692f.
van der Waals (vdW) intrinsic magnets are promising for miniaturization of devices beyond Moore's law for future energy efficient nanoelectronic devices and have been successfully used for constructing high performance vdW magnetic tunnel junctions (vdW MTJs). Here, using first principles calculations, we investigate the magnetic anisotropy, spin-dependent transport and tunneling magnetoresistance (TMR) effect of vdW MTJs formed by sandwiching a ferromagnetic (FM) monolayer CrI or non-magnetic monolayer ScI barrier between two vdW FM FeGeTe electrodes, respectively. It is found that two vdW MTJs possess strong perpendicular magnetic anisotropy. Moreover, due to no barrier for majority-spin transmission within half-metallic CrI barrier and the difference between majority- and minority-spin conduction channels of the FeGeTe electrode, a high TMR ratio of about 3100% is achieved in vdW MTJs based on the FeGeTe/CrI/FeGeTe vdW heterostructure. In contrast, a smaller TMR ratio of about 1200% is produced in vdW MTJs based on the FeGeTe/ScI/FeGeTe vdW heterostructure due to the strong suppression of ScI for majority-spin transmission in the case of the parallel state of magnetization of two FM electrodes. Our results provide a promising route for the design of vdW perpendicular MTJs with a high TMR ratio.
范德华（vdW）本征磁体对于超越摩尔定律的未来节能纳米电子器件的小型化很有前景，并且已成功用于构建高性能的范德华磁隧道结（vdW MTJs）。在此，我们使用第一性原理计算，分别研究了由铁磁（FM）单层CrI或非磁性单层ScI势垒夹在两个范德华FM FeGeTe电极之间形成的vdW MTJs的磁各向异性、自旋相关输运和隧道磁电阻（TMR）效应。结果发现，两种vdW MTJs都具有很强的垂直磁各向异性。此外，由于半金属CrI势垒内多数自旋传输无势垒以及FeGeTe电极的多数和少数自旋传导通道之间的差异，基于FeGeTe/CrI/FeGeTe范德华异质结构的vdW MTJs实现了约3100%的高TMR比。相比之下，基于FeGeTe/ScI/FeGeTe范德华异质结构的vdW MTJs在两个FM电极磁化平行状态下，由于ScI对多数自旋传输的强烈抑制，产生了约1200%的较小TMR比。我们的结果为设计具有高TMR比的vdW垂直MTJs提供了一条有前景的途径。
