Baghran R, Tehranchi M M, Phirouznia A
Department of Physics, Shahid Beheshti University, 1983963113 G.C., Evin, Tehran, Iran.
Department of Physics, Azarbaijan Shahid Madani University, Tabriz, 53714-161, Iran.
Sci Rep. 2021 Jul 22;11(1):14954. doi: 10.1038/s41598-021-94218-0.
Spin to pseudo-spin conversion by which the non-equilibrium normal sublattice pseudo-spin polarization could be achieved by magnetic field has been proposed in graphene. Calculations have been performed within the Kubo approach for both pure and disordered graphene including vertex corrections of impurities. Results indicate that the normal magnetic field [Formula: see text] produces pseudo-spin polarization in graphene regardless of whether the contribution of vertex corrections has been taken into account or not. This is because of non-vanishing correlation between the [Formula: see text] and [Formula: see text] provided by the co-existence of extrinsic Rashba and intrinsic spin-orbit interactions which combines normal spin and pseudo-spin. For the case of pure graphene, valley-symmetric spin to pseudo-spin response function is obtained. Meanwhile, by taking into account the vertex corrections of impurities the obtained response function is weakened by several orders of magnitude with non-identical contributions of different valleys. This valley-asymmetry originates from the inversion symmetry breaking generated by the scattering matrix. Finally, spin to pseudo-spin conversion in graphene could be realized as a practical technique for both generation and manipulation of normal sublattice pseudo-spin polarization by an accessible magnetic field in a easy way. This novel proposed effect not only offers the opportunity to selective manipulation of carrier densities on different sublattice but also could be employed in data transfer technology. The normal pseudo-spin polarization which manifests it self as electron population imbalance of different sublattices can be detected by optical spectroscopy measurements.
在石墨烯中已提出通过自旋到赝自旋的转换,利用磁场可实现非平衡正常子晶格的赝自旋极化。已采用久保方法对纯净和无序的石墨烯进行了计算,其中包括杂质的顶点修正。结果表明,无论是否考虑顶点修正的贡献,正常磁场[公式:见原文]都会在石墨烯中产生赝自旋极化。这是由于外在的 Rashba 相互作用和内在的自旋 - 轨道相互作用共存,使得[公式:见原文]和[公式:见原文]之间存在非零相关性,这两种相互作用将正常自旋和赝自旋结合在一起。对于纯净石墨烯的情况,得到了谷对称的自旋到赝自旋响应函数。同时,考虑杂质的顶点修正后,得到的响应函数减弱了几个数量级,且不同谷的贡献不相同。这种谷不对称性源于散射矩阵产生的宇称对称性破缺。最后,石墨烯中的自旋到赝自旋转换可以通过一个易于获得的磁场以一种简单的方式实现,作为一种产生和操纵正常子晶格赝自旋极化的实用技术。这种新提出的效应不仅为在不同子晶格上选择性地操纵载流子密度提供了机会,而且还可应用于数据传输技术。表现为不同子晶格电子数不平衡的正常赝自旋极化可以通过光谱测量来检测。