Hidden orbital polarization in diamond, silicon, germanium, gallium arsenide and layered materials

摘要

It was previously believed that the Bloch electronic states of non-magneticmaterials with inversion symmetry cannot have finite spin polarizations.However, since the seminal work by Zhang et al. [Nat. Phys. 10, 387-393 (2014)]on local spin polarizations of Bloch states in non-magnetic, centrosymmetricmaterials, the scope of spintronics has been significantly broadened. Here, weshow, using a framework that is universally applicable independent of whetherhidden spin polarizations are small (e.g., diamond, Si, Ge, and GaAs) or large(e.g., MoS2 and WSe2), that the corresponding quantity arising from orbital -instead of spin - degrees of freedom, the hidden orbital polarization, is (i)much more abundant in nature since it exists even without spin-orbit couplingand (ii) more fundamental since the interband matrix elements of thesite-dependent orbital angular momentum operator determines the hidden spinpolarization. We predict that the hidden spin polarization of transition metaldichalcogenides is reduced significantly upon compression. We suggestexperimental signatures of hidden orbital polarization from photoemissionspectroscopies and demonstrate that the current-induced hidden orbitalpolarization may play a far more important role than its spin counterpart inantiferromagnetic information technology by calculating the current-drivenantiferromagnetism in compressed silicon.