Materials Design of CuAlO_2-Based Dilute Magnetic Semiconductors by First-Principles Calculations and Monte Carlo Simulations

摘要

In order to propose a new dilute magnetic semicoductors (DMS) other than II-VI and III-V semiconductor based DMS, magnetism of CuAlO_2 based DMS is investigated by the Korringa-Kohn-Rostoker method combined with the coherent potential approximation within the local spin density approximation and Monte Carlo simulations (MCS). We found that effective exchange interactions (J_(ij)) between magnetic ions are short-ranged and J_(ij)'s between magnetic ions in the same Cu-plane are ferromagnetic and ones between the different Cu-planes are nearly negligible in CuAlO_2-based DMS. In comparison to this, J_(ij)'s between magnetic impurities occupied at Al-sites are slightly longer-ranged due to the stronger hybridization effect. According to MCS calculations, it is found that the value of the Curie temperature (T_C) exceeds 80 K in (Cu,Fe)AlO_2-and (Cu,Co)AlO_2-DMS and that the T_C is suppressed due to the strong percolation effect. This effect also appears in Cu(Al,TM)O_2, where TM denote 3d-transition metal elements.