Materials Design of CuAlO2-Based Dilute Magnetic Semiconductors by First-Principles Calculations and Monte Carlo Simulations

概要

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In order to propose a new dilute magnetic semicoductors (DMS) other than II–VI and III–V semiconductor based DMS, magnetism of CuAlO2 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 CuAlO2-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 ($T_{\text{C}}$) exceeds 80 K in (Cu,Fe)AlO2- and (Cu,Co)AlO2-DMS and that the $T_{\text{C}}$ is suppressed due to the strong percolation effect. This effect also appears in Cu(Al,TM)O2, where TM denote 3d-transition metal elements.
2008-08-25