Exact SU(2) Symmetry and Persistent Spin Helix in a Spin-Orbit Coupled System

B. Andrei Bernevig, J. Orenstein, and Shou-Cheng Zhang

Phys. Rev. Lett. 97, 236601 – Published 4 December 2006

Abstract

Spin-orbit coupled systems generally break the spin rotation symmetry. However, for a model with equal Rashba and Dresselhauss coupling constants, 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 wave vector depends on the coupling strength. It renders the spin lifetime infinite at this wave vector, giving rise to a persistent spin helix. We obtain the spin fluctuation dynamics at, and away from, the symmetry point and suggest experiments to observe the persistent spin helix.

Received 7 June 2006

DOI:https://doi.org/10.1103/PhysRevLett.97.236601

Authors & Affiliations

B. Andrei Bernevig^1,2, J. Orenstein^3,4, and Shou-Cheng Zhang¹

¹Department of Physics, McCullough Building, Stanford University, Stanford, California 94305-4045, USA
²Princeton Center for Theoretical Physics, Princeton University, Princeton, New Jersey 08544, USA
³Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
⁴Physics Department, University of California at Berkeley, Berkeley, California 94720, USA

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Issue

Vol. 97, Iss. 23 — 8 December 2006

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Physical Review Letters