Gauge-invariant theory of the Meissner effect in the lattice model of a superconductor with local pairing.
Gauge-invariant theory of the Meissner effect in the lattice model of a superconductor with local pairing.
复制标题
DOI：
10.1103/physrevb.49.6158
复制
发表时间：
1994-03
期刊：
影响因子：
--
通讯作者：
Kostyrko;Micnas;Chao
中科院分区：
文献类型：
--
作者：
Kostyrko;Micnas;Chao
利用负U-Hubbard哈密顿量和随机相近似(RPA)研究了超导体对静磁场响应的规范不变理论。我们将规范不变性的通常条件推广到超导体的紧束缚模型的情形，发现对于布里渊区的所有波矢，我们的RPA理论都能满足这一条件。同时，响应核的横向部分被集体效应修正，这与连续介质模型相反。我们发现，在弱耦合和强耦合两种情况下，响应核在长波长极限上都表现出显著的各向异性。结合正方形晶格的数值计算结果，我们考察了核的演化随耦合强度和能带填充的变化。
We study a gauge-invariant theory of the response of a superconductor to the static magnetic field using the negative-U Hubbard Hamiltonian and the random phase approximation (RPA). We extend the usual condition of the gauge invariance to the case of the tight-binding model of the superconductor and find it to be fulfilled by our RPA theory for all wave vectors in the Brillouin zone. At the same time the transverse part of the response kernel is modified by the collective effects, contrary to the continuum model. We find that the response kernel shows substantial anisotropy in the long-wavelength limit in both weak-and strong-coupling regimes. With the numerical results for the square lattice, we examine evolution of the kernel with the change of the coupling strength and band filling.