Hole carrier mediated magnetization in Cu-doped GaN is investigated by using the first-principles calculations.By studying the sp-d interaction and the direct exchange interaction among the dopants,we obtain an equation to determine the spontaneous magnetization as a function of the Cu dopant concentration and the hole carrier density.It is demonstrated that nonmagnetic Cu doped GaN can be of room-temperature ferromagnetism.The system's Curie temperature Tc can reach about 345 K with Cu concentration of 1.0% and hole carrier density of 5.0×1019 cm-3.The results are in good agreement with experimental observations and indicate that ferromagnetism in this systems is tunable by controlling the Cu concentration and the hole carrier density.
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