Nayak S K, Ogura M, Hucht A, Akai H, Entel P
Physics Department, University of Duisburg-Essen, 47048 Duisburg, Germany.
J Phys Condens Matter. 2009 Feb 11;21(6):064238. doi: 10.1088/0953-8984/21/6/064238. Epub 2009 Jan 20.
Co doped ZnO (Zn(1-x)Co(x)O) is studied as a prototype material for transition metal doped II-VI diluted magnetic semiconductors (DMSs) from first-principles and Monte Carlo simulations. The exchange interactions are calculated using the Korringa-Kohn-Rostoker (KKR) Green's function method. The exchange coupling constants thus obtained are treated in the classical Heisenberg model and the magnetic phase transitions are studied by the Monte Carlo technique. Our results show that the defect free substitutional DMSs of Zn(1-x)Co(x)O do not sustain magnetization at low concentration. At high concentration, we find layered magnetic structures. Ferromagnetism, with Curie temperature below room temperature, is stable at intermediate Co concentrations. First-principles studies with the generalized gradient approximation (GGA) and the GGA together with the Hubbard U are discussed with respect to structural and electronic properties of ZnO.
通过第一性原理和蒙特卡罗模拟，对共掺杂氧化锌（Zn(1-x)Co(x)O）作为过渡金属掺杂II - VI族稀磁半导体（DMS）的原型材料进行了研究。使用科林加 - 科恩 - 罗斯托克尔（KKR）格林函数方法计算交换相互作用。将由此获得的交换耦合常数应用于经典海森堡模型，并通过蒙特卡罗技术研究磁相变。我们的结果表明，在低浓度下，无缺陷替代的Zn(1-x)Co(x)O稀磁半导体不会保持磁化。在高浓度下，我们发现了层状磁结构。居里温度低于室温的铁磁性在中等钴浓度下是稳定的。针对氧化锌的结构和电子性质，讨论了采用广义梯度近似（GGA）以及GGA与哈伯德U相结合的第一性原理研究。
