First‐principles calculations on magnetism and exchange interactions in GaMnAs and GaMnAsP

Based on first principles calculations using a full potential linearized augmented plane wave (FP‐LAPW) method in the local spin density approximation (LSDA) we calculated the electronic and magnetic properties ofGa 1 − xMn x As andGa 1 − xMn x As 1 − yP y. The calculated electronic band structure and density of states of both diluted magnetic semiconductors (DMSs) are discussed. These results show a reduction in energy band gap inGa 1 − xMn x As doped with a small content of P atoms (6.25% atomic percent) compared to the undoped alloyGa 1 − xMn x As . Low exchange interaction constants, N 0 β , andJ Mn − Mn , and low exchange splitting,Δ x p d , are observed inGa 1 − xMn x As 1 − yP y . The total magnetic moment calculated forGa 1 − xMn x As 1 − yP yis mainly attributed to the Mn atom, whereas the contributions from Ga, As, and P are minimal. The difference between the magnetic properties ofGa 1 − xMn x As andGa 1 − xMn x As 1 − yP y  is also discussed.