超导材料的正常态下杂质锌引起的非均匀性

本文采用含有非磁性杂质的二维t-J模型来描述掺锌的高温氧化物超导材料,并利用非均匀双时格林函数理论对有限尺寸的材料进行了数值计算.在 Fermion-Spin 理论框架下,我们分别研究了非磁性杂质引起的电荷和自旋的不均匀性及对材料正常态特性的影响.我们发现:一方面非磁性杂质锌对其附近的自旋反铁磁关联有强烈的影响,能使周围的最近邻关联函数的绝对值比均匀情况增加很多;另一方面,空位子会受到其周围自旋的影响而出现相应的分布不均匀性,进而又影响自旋关联的不均匀性.并且,围绕杂质锌能够形成自旋激发和空位激发的局域态.

INHOMOGENEITY INTRODUCED BY Zn IMPURITY IN DOPED CUPRATES

Two-dimensional t-J model with nonmagnetic Zn impurities is studied based on the fermion-spin theory. Within an improved Green function theory,we perform numerical calculation for the finite lattices with periodic boundary conditions,and obtain the inhomogeneities of hole concentration and local antiferromagnetic correlations around the nomagneic Zn impurities. It is shown that the spin excitations are strongly influenced by the nonmagnetic impurities because the local antiferromagnetic correlations closest to the impurities are enhanced. The nearest-neighbor spin correlations also have strong effect to the energy of hole,as a result a bound state of hole is formed around the nonmagnetic Zn impurity.