Strain-tuned magnetic properties in (Ga,Fe)Sb: First-principles study

In view of the importance of enhancing ferromagnetic (FM) coupling in dilute magnetic semiconductors (DMSs), the effects of strain on the electronic structures and magnetic properties of (Ga,Fe)Sb were examined by a first-principles study. The results of the investigation indicate that Fe_{m Ga} substitution takes place in the low-spin state (LSS) with a total magnetic moment of 1μ_B in the strain range of -3% to 0.5%, which transitions to the high-spin state (HSS) with a total magnetic moment of 5μ_B as the strain changes from 0.6% to 3%. We attribute the changes in the amount and distribution of the total moment to the influence of the crystal field under different strains. The FM coupling is strongest under a strain of about 0.5%, but gradually becomes weaker with increasing compressive and tensile strains. The magnetic coupling mechanism is discussed in detail. Our results highlight the important contribution of strain to magnetic moment and FM interaction intensity, and present an interesting avenue for the future design of high Curie temperature (T_C) materials in the (Ga,Fe)Sb system.