Persistent spin helix on a wurtzite ZnO$(10\bar{1}0)$ surface: First-principles density-functional study

Abstract

The persistent spin helix (PSH) that has been widely and exclusively studied in zinc-blende structures is revealed for the first time on the surface of a wurtzite structure. Through first principles calculations of the surface of ZnOð1010Þ, a quasi-one-dimensional orientation of the spin textures is identified. Furthermore, the wavelength of this particular PSH is smaller than that observed in various zinc-blende quantum well structures, thus indicating that wurtzite-structured surfaces are suitable for spintronics applications.

Spin-split bands of metallic hydrogenated ZnO (101¯) surface: First-principles study

“…In the case of ZnO (1010)-2H surface, we find that the electric polarization in the in-plane ∆P y and out-of-plane . 22 The larger value of the in-plane electric polarization ∆P y indicates that the electric field in the in-plane direction E y is enhanced, which is expected to induce Thus far, we have found that hydrogen termination on the ZnO (1010) surface induces a Rashba effect with a strong anisotropic character. Here, we find that the Rashba coupling parameter (α R ) has some substantial values, estimated from the band dispersion in Fig.…”

“…Furthermore, the strong anisotropic character of Rashba splitting predicted in the present study should ensure that carriers have an extended spin lifetime, [41][42][43] which is promising for energy-saving spintronics devices. 22 Therefore, this finding opens a possibility to realized spintronics devices using oxide electronic surface materials.…”

“…[35][36][37][38] In our past study, we clarified that the ZnO (1010) surface belongs to the symmetry point group C s , where the mirror reflections in operation in this symmetry transform (x, y, z) to (−x, y, z). 22 In this case, SOI can be expressed as 22…”

“…To confirm this, we calculate the layer-dependence of the electric polarization by using a point charge model (PCM) for Zn 2+ and O 2− ions in every bilayer. The polarization difference relative to the ideal surface system is expressed by 21,22 …”

“…20 In a past study, we have found that the Rashba splitting is observed in the bulk and surface systems of ZnO. 21,22 Furthermore, it was reported that a metallic surface-state is observed 23,24 when a ZnO (1010) surface is hydrogenated, indicating that this system can produce significant spin transport. On the other hand, the ZnO (1010) surface is energetically stable as the electrostatic instability of two polar surface terminations 25 can be avoided.…”