Spin-subband populations and spin polarization of quasi-two-dimensional carriers under an in-plane magnetic field

Abstract

Under an in-plane magnetic field, the density of states of quasi-two-dimensional carriers deviates from the occasionally stereotypic step-like form both quantitatively and qualitatively. Here we study how this affects the spin-subband populations and the spin-polarization as functions of the temperature, $T$, and the in-plane magnetic field, $B$, for narrow to wide dilute-magnetic-semiconductor quantum wells. We examine a wide range of material and structural parameters, focusing on the quantum well width, the magnitude of the spin-spin exchange interaction, and the sheet carrier concentration. Generally, increasing $T$, the carrier spin-splitting, ${U}_{o\ensuremath{\sigma}}$, decreases, augmenting the influence of the ``minority''-spin carriers. Increasing $B$, ${U}_{o\ensuremath{\sigma}}$, increases and, accordingly, carriers populate ``majority''-spin subbands while they abandon ``minority''-spin subbands. Furthermore, in line with the density of states modification, all energetically higher subbands become gradually depopulated. We also indicate the ranges where the system is completely spin-polarized.