Chiral Bloch states in single layer graphene with Rashba spin-orbit coupling: Spectrum and spin current density

Abstract

We study the Bloch spectrum and spin physics of 2D massless Dirac electrons in single layer graphene subject to a one dimensional periodic Kronig-Penney potential and Rashba spin-orbit coupling. The Klein paradox exposes novel features in the band dispersion and in graphene spintronics. In particular it is shown that: (1) The Bloch energy dispersion $\veps(p)$ has unusual structure: There are {\it two Dirac points} at Bloch momenta $\pm p\ne 0$ and a narrow band emerges between the wide valence and conduction bands. (2) The charge current and the spin density vector vanish. (3) Yet, all the non-diagonal elements of the spin current density tensor are finite and their magnitude increases linearly with the spin-orbit strength. In particular, there is a spin density current whose polarization is perpendicular to the graphene plane. (4) The spin density currents are space-dependent, hence their continuity equation includes a finite spin torque density.

arXiv commentsix pages five figures. arXiv admin note: text overlap with arXiv:2012.10971

References in corpus (22)

• Spintronics: Fundamentals and applications
• Chiral tunneling and the Klein paradox in graphene
• Graphene Spintronics
• Andreev reflection and Klein tunneling in graphene
• Selective transmission of Dirac electrons and ballistic magnetoresistance of \textit{n-p} junctions in graphene
• Colloquium: Spintronics in graphene and other two-dimensional materials
• On A Proper Definition of Spin Current
• Graphene on transition-metal dichalcogenides: a platform for proximity spin-orbit physics and optospintronics
• Klein tunneling in graphene: optics with massless electrons
• Spin currents and spin superfluidity
• The angular spin current and its physical consequences
• The definition of the spin current: The angular spin current and its physical consequences
• Persistent spin current in nano-devices and definition of the spin current
• Chiral tunneling in single and bilayer graphene
• Spin-dependent Klein tunneling in graphene: Role of Rashba spin-orbit coupling
• Persistent spin current in a spin-orbit coupling/normal hybrid ring
• Spin Orbit Coupling in Graphene Induced by Heavy Adatoms with Electrons in the Outer-Shell $p$ Orbitals
• Symmetries of quantum transport with Rashba spin-orbit: Graphene spintronics
• Mechanical measurement of equilibrium spin currents in the Rashba medium
• Spin-polarized currents in corrugated graphene nanoribbons
• Simple spin-orbit based devices for electron spin polarization
• Chiral tunneling in single layer graphene with Rashba spin-orbit coupling: spin currents