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Title: Theoretical study of cubic Rashba effect at SrTiO 3 (001) surfaces

Abstract

The origin of Rashba spin splitting in the two-dimensional electron gas at the (001) surface of SrTiO 3 is studied using first-principles calculations and tight-binding model. Calculations of oxygen vacancies under virtual crystal approximation reveal a two-dimensional electron-gas subband structure similar to polar materials, consistent with observations on SrTiO 3. Our studies also confirm that k dependence of the spin splitting is predominantly cubic in the surface Ti–t 2g states, even though structural relaxations diminish the effect in d xy bands. A tight-binding model, explicitly including Ti–d and O–p states as well as next-nearest-neighbor interactions, is derived to understand the first-principles results. Effective Rashba Hamiltonians for the surface bands are derived using quasidegenerate perturbation theory and scenarios in which linear k contribution may be suppressed are discussed. Furthermore, the cubic terms in the Hamiltonian are found to be different from the model derived using k ∙ p theory, leading to different pseudospin symmetry in the Brillouin zone.

Authors:
 [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1235844
Alternate Identifier(s):
OSTI ID: 1234307; OSTI ID: 1336595
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 93; Journal Issue: 4; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats

Shanavas, Kavungal Veedu. Theoretical study of cubic Rashba effect at SrTiO3 (001) surfaces. United States: N. p., 2016. Web. doi:10.1103/PhysRevB.93.045108.
Shanavas, Kavungal Veedu. Theoretical study of cubic Rashba effect at SrTiO3 (001) surfaces. United States. doi:10.1103/PhysRevB.93.045108.
Shanavas, Kavungal Veedu. Mon . "Theoretical study of cubic Rashba effect at SrTiO3 (001) surfaces". United States. doi:10.1103/PhysRevB.93.045108. https://www.osti.gov/servlets/purl/1235844.
@article{osti_1235844,
title = {Theoretical study of cubic Rashba effect at SrTiO3 (001) surfaces},
author = {Shanavas, Kavungal Veedu},
abstractNote = {The origin of Rashba spin splitting in the two-dimensional electron gas at the (001) surface of SrTiO3 is studied using first-principles calculations and tight-binding model. Calculations of oxygen vacancies under virtual crystal approximation reveal a two-dimensional electron-gas subband structure similar to polar materials, consistent with observations on SrTiO3. Our studies also confirm that k dependence of the spin splitting is predominantly cubic in the surface Ti–t2g states, even though structural relaxations diminish the effect in dxy bands. A tight-binding model, explicitly including Ti–d and O–p states as well as next-nearest-neighbor interactions, is derived to understand the first-principles results. Effective Rashba Hamiltonians for the surface bands are derived using quasidegenerate perturbation theory and scenarios in which linear k contribution may be suppressed are discussed. Furthermore, the cubic terms in the Hamiltonian are found to be different from the model derived using k ∙ p theory, leading to different pseudospin symmetry in the Brillouin zone.},
doi = {10.1103/PhysRevB.93.045108},
journal = {Physical Review B},
number = 4,
volume = 93,
place = {United States},
year = {2016},
month = {1}
}

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