Department of Physics, Nanjing Normal University, Nanjing 210097, People's Republic of China.
J Phys Condens Matter. 2010 May 26;22(20):206003. doi: 10.1088/0953-8984/22/20/206003. Epub 2010 Apr 26.
We have investigated the structural, electronic, and magnetic properties of Mn(3)Cu(1 - x)Ge(x)N (x = 0, 0.125, 0.25) using first-principles density-functional theory within the generalized gradient approximation (GGA) + U schemes. The crystal structure of the compounds is a tetragonal crystal for x = 0 while it is a cubic crystal for x = 0.125, 0.25. The unit cell volume increases as the Ge doping increases. Our GGA + U calculations give a metallic ground state from x = 0 to 0.25 in agreement with experiments. The magnetic structure for x = 0 is found to be the ferromagnetic state while for x = 0.125, 0.25 it is the Γ(5g)-type antiferromagnetic state. From the density of states (DOS), the coupling between Ge 4p and Mn 3d is the main reason for magnetic transition in Mn(3)Cu(1 - x)Ge(x)N.
我们使用第一性原理密度泛函理论（GGA+U 方案）研究了 Mn(3)Cu(1 - x)Ge(x)N（x = 0, 0.125, 0.25）的结构、电子和磁性质。化合物的晶体结构对于 x = 0 为四方晶系，对于 x = 0.125, 0.25 为立方晶系。随着 Ge 掺杂量的增加，晶胞体积增大。我们的 GGA+U 计算表明，从 x = 0 到 0.25，基态为金属态，这与实验结果一致。对于 x = 0，磁结构被发现为铁磁态，而对于 x = 0.125, 0.25，它是 Γ(5g)-型反铁磁态。从态密度（DOS）来看，Ge 4p 和 Mn 3d 之间的耦合是 Mn(3)Cu(1 - x)Ge(x)N 磁转变的主要原因。
