Hidden spin polarization in inversion-symmetric bulk crystals

 Xiuwen Zhang1,2,3†,Qihang Liu1,4†,Jun-Wei Luo3*,Arthur J. Freeman4 and Alex Zunger1*

 Abtract

 Spin–orbitcoupling can induce spin polarization in nonmagnetic 3D crystals when the inversion symmetry is broken,as manifested by the bulk Rashba and Dresselhaus effects. We establish that these spin-polarization effects originatefundamentally from specific atomic site asymmetries, rather than, as generally accepted, from the asymmetry of the crystalspace group. This understanding leads to the recognition that a previously overlooked hidden form of spin polarization shouldexist in centrosymmetric crystals. Although all energy bands must be doubly degenerate in centrosymmetric materials, wefind that the two components of such doubly degenerate bands could have opposite polarizations, each spatially localized onone of the two separate sectors forming the inversion partners. We demonstrate such hidden spin polarizations in particularcentrosymmetric crystals by first-principles calculations. This new understanding could considerably broaden the range ofcurrently useful spintronic materials and enable the control of spin polarization by means of operations on the atomic scale.

 

 https://sci-hub.se/https://arxiv.org/abs/1402.4446