Quasi two-dimensional carriers in dilute-magnetic-semiconductor quantum wells under in-plane magnetic field

TL;DR

This paper investigates how in-plane magnetic fields and temperature affect spin polarization and subband populations in dilute-magnetic-semiconductor quantum wells, considering the effects of quantum confinement and density of states modifications.

Contribution

It provides a detailed analysis of spin polarization behavior in quasi-two-dimensional systems under magnetic fields, accounting for density of states deviations and quantum well parameters.

Findings

Spin-splitting decreases with temperature increase.

Higher magnetic fields enhance spin-splitting.

Density of states modifications lead to depopulation of higher subbands.

Abstract

Due to the competition between spatial and magnetic confinement, the density of states of a quasi two-dimensional system deviates from the ideal step-like form both quantitatively and qualitatively. 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 focus on the quantum well width, the magnitude of the spin-spin exchange interaction, and the sheet carrier concentration dependence. We look for ranges where the system is completely spin-polarized. Increasing $T$, the carrier spin-splitting, $U_{o\sigma}$, decreases, while increasing $B$, $U_{o\sigma}$ increases. Moreover, due to the density of states modification, all energetically higher subbands become gradually depopulated.