Electronic and optical spectra in a diluted magnetic semiconductor multilayer

TL;DR

This study investigates how magnetic impurities affect the electronic and optical properties of semiconductor multilayers, revealing layer-dependent effects, broadening due to spin fluctuations, and energy gap formation under strong exchange interactions.

Contribution

It introduces a detailed analysis of magnetic impurity effects on spectra in multilayer semiconductors using coherent potential approximation and tight-binding models.

Findings

Density of states and optical absorption are layer-dependent.

Spin fluctuations cause spectral broadening.

Strong exchange interactions lead to an energy gap.

Abstract

The effects of random distribution of magnetic impurities with concentration $x$ in a semiconductor alloy multilayer at a paramagnetic temperature are investigated by means of coherent potential approximation and tight-binding model. The change in the electronic states and the optical absorption spectrum with $x$ is calculated for weak and strong exchange interactions between carrier spins and localized spin moments on magnetic ions. We find that the density of states and optical absorption are strongly layer-dependent due to the quantum size effects. The electronic and optical spectra are broadened due to the spin fluctuations of magnetic ions and in the case of strong exchange interaction, an energy gap appears in both spectra. Furthermore, the interior layers show higher contribution in the optical absorption of the system. The results can be helpful for magneto-optical devices at a paramagnetic temperature.