Single-Band Model for Diluted Magnetic Semiconductors: Dynamical and Transport Properties and Relevance of Clustered States

TL;DR

This paper uses Monte Carlo simulations of a single-band spin-fermion model to explore the dynamical and transport properties of diluted magnetic semiconductors, highlighting the significance of clustered states and intermediate coupling regimes.

Contribution

It provides new insights into the role of clustered states and intermediate coupling in DMS, supported by transport and optical property calculations.

Findings

Resistivity shows a soft metal-insulator transition near T_C

Large magnetoresistance observed in clustered regimes

Density-of-states and optical conductivity analyses support partial carrier trapping

Abstract

Dynamical and transport properties of a simple single-band spin-fermion lattice model for (III,Mn)V diluted magnetic semiconductors (DMS) is here discussed using Monte Carlo simulations. This effort is a continuation of previous work (G. Alvarez, Phys. Rev. Lett. 89, 277202 (2002)) where the static properties of the model were studied. The present results support the view that the relevant regime of J/t (standard notation) is that of intermediate coupling, where carriers are only partially trapped near Mn spins, and locally ordered regions (clusters) are present above the Curie temperature T_C. This conclusion is based on the calculation of the resistivity vs. temperature, that shows a soft metal to insulator transition near T_C, as well on the analysis of the density-of-states and optical conductivity. In addition, in the clustered regime a large magnetoresistance is observed in simulations. Formal analogies between DMS and manganites are also discussed.