Fizika Nizkikh Temperatur: Volume 45, Number 2 (February 2019), p. 185-192 ( to contents , go back )
Spin splitting of surface states in HgTe quantum wells
A.A. Dobretsova1,2, Z.D. Kvon1,2, S.S. Krishtopenko3,4, N.N. Mikhailov1, and S.A. Dvoretsky1
1Rzhanov Institute of Semiconductor Physics, Novosibirsk 630090, Russia
2Novosibirsk State University, Novosibirsk 630090, Russia
3Institute for Physics of Microstructures RAS, GSP-105, Nizhni Novgorod 603950, Russia
4Laboratoire Charles Coulomb, UMR CNRS 5221, University of Montpellier, Montpellier 34095, France
Received October 11, 2018, published online December 20, 2018
We report on beating appearance in Shubnikov–de Haas oscillations in conduction band of 18–22 nm HgTe quantum wells under applied top-gate voltage. Analysis of the beatings reveals two electron concentrations at the Fermi level arising due to Rashba-like spin splitting of the first conduction subband H1. The difference ΔNs in two concentrations as a function of the gate voltage is qualitatively explained by a proposed toy electrostatic model involving the surface states localized at quantum well interfaces. Experimental values of ΔNs are also in a good quantitative agreement with self-consistent calculations of Poisson and Schrödinger equations with eight-band k · p Hamiltonian. Our results clearly demonstrate that the large spin splitting of the first conduction subband is caused by surface nature of H1 states hybridized with the heavy-hole band.
Key words: spin splitting, Rashba effect, surface states, Shubnikov–de Haas oscillations, quantum wells.