Gauge covariance and spin-current conservation in the gauge-field formulation of systems with spin-orbit coupling

The question of gauge covariance in the non-Abelian gauge-field formulation of two space-dimensional systems with spin-orbit coupling relevant to spintronics is investigated. Although these are generally gauge-fixed models, it is found that for the class of gauge fields that are spacetime independen...

Full description

Saved in:
Bibliographic Details
Published inJournal of physics. A, Mathematical and theoretical Vol. 45; no. 10; pp. 105305 - 13
Main Authors Shikakhwa, M S, Turgut, S, Pak, N K
Format Journal Article
LanguageEnglish
Published Bristol IOP Publishing 16.03.2012
IOP
Subjects
Covariance
Density
Derivation
Exact sciences and technology
Gages
gauge symmetry
Gauges
Mathematical models
Physics
spin current
Spin-orbit interactions
Transformations
Transformations (mathematics)
Continuity equations
Two-dimensional systems
Two dimensional space
Spin systems
Gauge transformation
Gauge fixing
Rotation axis
Spin density
Space-time
Gauge field
Covariance
Hamiltonians
Free particle
Spin-orbit interactions
Wave functions
Models
Rotation angle
Online AccessGet full text

Cover

More Information
Summary:The question of gauge covariance in the non-Abelian gauge-field formulation of two space-dimensional systems with spin-orbit coupling relevant to spintronics is investigated. Although these are generally gauge-fixed models, it is found that for the class of gauge fields that are spacetime independent and satisfy a U(1) algebra, thus having a vanishing field strength, there is a residual gauge freedom in the Hamiltonian. The gauge transformations assume the form of a space-dependent rotation of the transformed wavefunctions with rotation angles and axes determined by the specific form of the gauge field, i.e. the spin-orbit coupling. The fields can be gauged away, reducing the Hamiltonian to one which is isospectral to the free-particle Hamiltonian, and giving rise to the phenomenon of persistent spin helix reported first by Bernevig et al (2006 Phys. Rev. Lett. 97 236601). The investigation of the global gauge transformations leads to the derivation of a continuity equation where the component of the spin density along given directions, again fixed by the specific form of the gauge field, is conserved.
Bibliography:ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
content type line 23
ISSN:1751-8113
1751-8121
DOI:10.1088/1751-8113/45/10/105305