La_2CuO_4类反铁磁体的低温磁学性质

Low-Temperature Magnetic Properties of Antiferromagnetic La_2CuO_4

考虑到高 T_C 氧化物具有层状结构特点,从量子 Heisenberg 模型出发,用自旋波理论研究了 La_2CuO_4类化合物的低温磁学性质.通过矩阵格林函数运动方程技术,计算了层间耦合 J_1和 J_2(分别对应层间反向和同向自旋间的交换作用)对系统的子晶格磁化强度、内能、磁比热、平行和垂直磁化率等物理量的影响.结果表明,在 J_1(J_2)小于10^(-2)J 量级时,各物理量主要与 J_1和 J_2的差有关,与它们自身的大小关系不大.

Considering the layered structural characteristics of high-Tc oxides,we studied the low-temper- ature magnetic properties of antiferromagnetic La_2CuO_4 based on quantum Heisenberg model by using spin- wave theory.Applying the technique of equation of motion for matrix Green functioon,we calculated the ef- fect of interlaye coupling J_1 and J_2,which are the interlayer couplings in the a-b plane and in the b-c plane re- spectively,on the physical quantities of system,such as sublattice magnetization,internal energy,magnetic specific heat,parallel and perpendicular susceptibilities.The results show that when J_1 and J_2 are smaller than 10^(-2)J,the physical quantities are mainly dependent on the difference of J_1 and J_2,depending little on their own values.