Understanding ferromagnetism in C-doped CdS: Monte Carlo simulation

Abstract

Room-temperature ferromagnetism of diluted magnetic semiconductors (DMSs) doped with light elements has been extensively investigated for potential applications in spintronic devices. Indeed, the mechanism underlying ferromagnetism in DMSs of low concentrations has been studied from both theoretical and experimental perspectives. Theoretically, first-principles calculation and Monte Carlo (MC) simulation were combined together to study electronic and magnetic properties of DMSs. The Curie temperature of DMSs has been usually estimated from Monte Carlo simulation. In particular, MC simulations use both continuous and discrete spin models to describe the spin state in the ferromagnetic phase of DMSs. Nevertheless, which of the two models is the more appropriate is unclear. To clarify further this issue of ”continuous versus discrete” spin model in DMS materials, we have performed a large-scale MC simulation for C-doped CdS material. The discrete spin model sets the ferromagnetic phase transition below room-temperature whereas the continuous spin model sets this transition at rather low temperatures. The discrete spin model is found to describe more appropriately the spin state of C atoms in the C-doped CdS.