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Title: An Exact SU(2) Symmetry and Persistent Spin Helix ina Spin-orbit Coupled System

Abstract

Spin-orbit coupled systems generally break the spin rotation symmetry. However, for a model with equal Rashba and Dresselhauss coupling constant (the ReD model), and for the [110] Dresselhauss model, a new type of SU(2) spin rotation symmetry is discovered. This symmetry is robust against spin-independent disorder and interactions, and is generated by operators whose wavevector depends on the coupling strength. It renders the spin lifetime infinite at this wavevector, giving rise to a Persistent Spin Helix (PSH). We obtain the spin fluctuation dynamics at, and away, from the symmetry point, and suggest experiments to observe the PSH.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Stanford Linear Accelerator Center (SLAC)
Sponsoring Org.:
USDOE
OSTI Identifier:
898147
Report Number(s):
SLAC-PUB-12313
TRN: US0700572
DOE Contract Number:
AC02-76SF00515
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Lettters
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; SU-2 GROUPS; COUPLING CONSTANTS; FLUCTUATIONS; LIFETIME; ROTATION; SPIN; SYMMETRY; Accelerators,ACCSYS

Citation Formats

Bernevig, B.A., /Stanford U., Phys. Dept. /Santa Barbara, KITP, Orenstein, J., /LBL, Berkeley /UC, Berkeley, Zhang, Shou-Cheng, and /Stanford U., Phys. Dept. An Exact SU(2) Symmetry and Persistent Spin Helix ina Spin-orbit Coupled System. United States: N. p., 2007. Web.
Bernevig, B.A., /Stanford U., Phys. Dept. /Santa Barbara, KITP, Orenstein, J., /LBL, Berkeley /UC, Berkeley, Zhang, Shou-Cheng, & /Stanford U., Phys. Dept. An Exact SU(2) Symmetry and Persistent Spin Helix ina Spin-orbit Coupled System. United States.
Bernevig, B.A., /Stanford U., Phys. Dept. /Santa Barbara, KITP, Orenstein, J., /LBL, Berkeley /UC, Berkeley, Zhang, Shou-Cheng, and /Stanford U., Phys. Dept. Mon . "An Exact SU(2) Symmetry and Persistent Spin Helix ina Spin-orbit Coupled System". United States. doi:. https://www.osti.gov/servlets/purl/898147.
@article{osti_898147,
title = {An Exact SU(2) Symmetry and Persistent Spin Helix ina Spin-orbit Coupled System},
author = {Bernevig, B.A. and /Stanford U., Phys. Dept. /Santa Barbara, KITP and Orenstein, J. and /LBL, Berkeley /UC, Berkeley and Zhang, Shou-Cheng and /Stanford U., Phys. Dept.},
abstractNote = {Spin-orbit coupled systems generally break the spin rotation symmetry. However, for a model with equal Rashba and Dresselhauss coupling constant (the ReD model), and for the [110] Dresselhauss model, a new type of SU(2) spin rotation symmetry is discovered. This symmetry is robust against spin-independent disorder and interactions, and is generated by operators whose wavevector depends on the coupling strength. It renders the spin lifetime infinite at this wavevector, giving rise to a Persistent Spin Helix (PSH). We obtain the spin fluctuation dynamics at, and away, from the symmetry point, and suggest experiments to observe the PSH.},
doi = {},
journal = {Physical Review Lettters},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 22 00:00:00 EST 2007},
month = {Mon Jan 22 00:00:00 EST 2007}
}
  • Spin-orbit coupled systems generally break the spin rotation symmetry. However, for a model with equal Rashba and Dresselhauss coupling constant (the ReD model), and for the [110] Dresselhauss model, a new type of SU(2) spin rotation symmetry is discovered. This symmetry is robust against spin-independent disorder and interactions, and is generated by operators whose wavevector depends on the coupling strength. It renders the spin lifetime infinite at this wavevector, giving rise to a Persistent Spin Helix (PSH). We obtain the spin fluctuation dynamics at, and away, from the symmetry point, and suggest experiments to observe the PSH.
  • We present the spin-orbit (SO) and Renner-Teller (RT) quantum dynamics of the spin-forbidden quenching O({sup 1}D) + N{sub 2}(X{sup 1}{Sigma}{sub g}{sup +}){yields}O({sup 3}P) + N{sub 2}(X{sup 1}{Sigma}{sub g}{sup +}) on the N{sub 2}O X-tilde{sup 1}A{sup '}, a-tilde{sup 3}A', and b-tilde{sup 3}A{sup '} coupled PESs. We use the permutation-inversion symmetry, propagate coupled-channel (CC) real wavepackets, and compute initial-state-resolved probabilities and cross sections {sigma}{sub j0} for the ground vibrational and the first two rotational states of N{sub 2}, j{sub 0}= 0 and 1. Labeling symmetry angular states by j and K, we report selection rules for j and for the minimum Kmore » value associated with any electronic state, showing that a-tilde{sup 3}A' is uncoupled in the centrifugal-sudden (CS) approximation at j{sub 0}= 0. The dynamics is resonance-dominated, the probabilities are larger at low K, {sigma}{sub j0} decrease with the collision energy and increase with j{sub 0}, and the CS {sigma}{sub 0} is lower than the CC one. The nonadiabatic interactions play different roles on the quenching dynamics, because the X-tilde{sup 1}A{sup '}-b-tilde{sup 3}A{sup '} SO effects are those most important while the a-tilde{sup 3}A'-b-tilde{sup 3}A{sup '} RT ones are negligible.« less
  • We demonstrate gate-controlled switching between persistent spin helix (PSH) state and inverse PSH state, which are detected by quantum interference effect on magneto-conductance. These special symmetric spin states showing weak localization effect give rise to a long spin coherence when the strength of Rashba spin-orbit interaction (SOI) is close to that of Dresselhaus SOI. Furthermore, in the middle of two persistent spin helix states, where the Rashba SOI can be negligible, the bulk Dresselhaus SOI parameter in a modulation doped InGaAs/InAlAs quantum well is determined.
  • In this paper we use a spin kinetic equation to study spin-polarization dynamics in one-dimensional (1D) wires and 2D channels. The spin kinetic equation is valid in both diffusive and ballistic spin transport regimes and therefore is more general than the usual spin drift-diffusion equations. In particular, we demonstrate that in infinite 1D wires with Rashba spin-orbit interaction the exponential spin-relaxation decay can be modulated by an oscillating function. In the case of spin relaxation in finite length 1D wires, it is shown that an initially homogeneous spin polarization spontaneously transforms into a persistent spin helix. We find that amore » propagating spin-polarization profile reflects from a system boundary and returns back to its initial position similarly to the reflectance of sound waves from an obstacle. The Green's function of the spin kinetic equation is derived for both finite and infinite 1D systems. Moreover, we demonstrate explicitly that the spin relaxation in specifically oriented 2D channels with Rashba and Dresselhaus spin-orbit interactions of equal strength occurs similarly to that in 1D wires of finite length. Finally, a simple transformation mapping 1D spin kinetic equation into the Klein-Gordon equation with an imaginary mass is found thus establishing an interesting connection between semiconductor spintronics and relativistic quantum mechanics.« less