Laser-field-mediated Rashba and Dresselhaus spin–orbit control in GaInAs/AlInAs quantum wells

Abstract

For more possibilities in exploring the spin–orbit (SO) control in two-dimensional (2D) semiconductor quantum wells, we resort to the laser field by constructing a generic model including both the axial and transverse field components relative to the well-growth direction, with the axial one primarily modifying the structural potential of the well and the transverse one mainly altering the electron density of states and so the Hartree potential. For GaInAs/AlInAs quantum wells with two-subband occupation, we obtain the full scenario of the laser-field response of the Rashba and Dresselhaus SO couplings, including both the intrasubband (αν and βν with ν = 1,2 denoting the subband index) and intersubband (η and Γ) types, by solving the Poisson–Schrödinger equations. Remarkably, for the Dresselhaus coupling, which is insensitive to the electrical manipulation, we demonstrate that it can be substantially tuned by the laser field and unified SO control of different subbands is possible, suggesting that the optical manner is an effective supplement to the electrical means. Moreover, symmetric (α1=−α2) and selective (α1=0, α2≠0) control of the Rashba coupling of different subbands are also observed with the interplay of the two laser components, which are desirable for the realization of skyrmion lattice and the suppression of spin relaxation of given subbands. Besides, for the intersubband coupling, the Rashba term η is optically tunable while the Dresselhaus term Γ is basically immune to the laser field, i.e., selective control of the intersubband coupling by virtue of optical means. These diverse laser-field-mediated SO features offer exciting possibilities in incorporating 2D quantum wells for new applications in the field of spintronics.