Optimizing TcTc in the (Mn,Cr,Ga)As and (Mn,Ga)(As,P) ternary alloys

We explore two possible ways to enhance the critical temperature TcTc in the dilute magnetic semiconductor Mn0.08Ga0.92AsMn0.08Ga0.92As. Within the context of the double-exchange and RKKY pictures, the ternary alloys MnxCr0.08-xGa0.92AsMnxCr0.08-xGa0.92As and Mn0.08Ga0.92AsyP1-yMn0.08Ga0.92AsyP1-y might be expected to have TcTc higher than the pseudobinary Mn0.08Ga0.92AsMn0.08Ga0.92As. To test whether the expectations from model pictures are confirmed, we employ linear response theory within the local-density approximation to search for theoretically higher critical temperatures in these ternary alloys. Our results show that neither co-doping Mn with Cr, nor alloying As with P improves TcTc. Alloying with Cr is found to be deleterious to the TcTc. Mn0.08Ga0.92AsyP1-yMn0.08Ga0.92AsyP1-y shows almost linear dependence of TcTc on yy.