Tunable Surface Electron Spin Splitting with Electric Double-Layer Transistors Based on InN

Abstract

Electrically manipulating electron spins based on Rashba spin-orbit coupling (SOC) is a key pathway for applications of spintronics and spin-based quantum computation. Two-dimensional electron systems (2DESs) offer a particularly important SOC platform, where spin polarization can be tuned with an electric field perpendicular to the 2DES. Here, by measuring the tunable circular photogalvanic effect (CPGE), we present a room-temperature electric-field-modulated spin splitting of surface electrons on InN epitaxial thin films that is a good candidate to realize spin injection. The surface band bending and resulting CPGE current are successfully modulated by ionic liquid gating within an electric double-layer transistor configuration. The clear gate voltage dependence of CPGE current indicates that the spin splitting of the surface electron accumulation layer is effectively tuned, providing a way to modulate the injected spin polarization in potential spintronic devices.

Rashba and Dresselhaus Effects in Hybrid Organic–Inorganic Perovskites: From Basics to Devices

“…Contrary to the previous examples, 38,39,[73][74][75][76][77][78][79] the suggested setup presents no manifestation of the SOC in terms of spin 19 splitting (l R = 0 eV.Å) when the electric field is switched off, which makes less delicate the tuning of the source-drain distance and of the amplitude of the transverse field.…”

“…After the very first observations of tunable Rashba splitting, [21][22][23] several examples of devices have been produced 38,39,73,74 or proposed on the basis of theoretical inspections. 75,76 More elaborated devices have been proposed based on the same principle, adding a transverse magnetic field to the electric one and using more than one site for SOC effect.…”

Identification of Helicity-Dependent Photocurrents from Topological Surface States in Bi2Se3 Gated by Ionic Liquid

“…This is the key advance of this work along with the multiple advantages of ILG over the conventional solid gates202122. The ionic liquid together with the sample and the gate electrode forms an electric double-layer transistor geometry, where the interfaces could be regarded as nano-gap capacitors with huge capacitance, resulting in very high electron-density tunability23.…”

“…From the measurement, the density of electrons in the sample is tuned from 4.94 × 10 13  cm −2 to 7.48 × 10 13  cm −2 in the gate-voltage range varying from −0.9 V to 1.2 V. Further increase of the magnitude of the gate voltage will cause saturation20. Surface electric field induced by the electron accumulation could be obtained according to the Poisson equation E s = qN s / ε 0 ε TI , where E s is the surface electric field, q the elementary charge, N s the surface electron density, ε 0 the vacuum dielectric permittivity, and ε TI ~ 113 the dielectric permittivity of Bi 2 Se 3 2024. From the change of the density of electrons given above, the surface electric field is tuned as much as 0.43 MV/cm.…”

“…The SEAL in the samples was modulated by ionic liquid gate (ILG)202122. The clear gate-voltage dependence of the density of electrons and HDP signal shows that the band bending as well as the Rashba spin-orbit splitting of SEAL are successfully modulated by the ILG.…”