Electronic structure of the vortex lattice ofd−,d+is−,andd

Abstract

On the basis of the self-consistent Bogoliubov-de Gennes equations and a tight-binding lattice model, we investigate the quasiparticle spectrum of vortex-lattice state in pure d-, mixed dϩis, and d x 2 Ϫy 2ϩ id xy-wave superconductors. For a d-wave case, the local density of states ͑LDOS͒ at the vortex core shows a multipeak structure, and the positions of peaks as well as the width of splitting between peaks are sensitively dependent on both the magnetic-field strength and the orientation of the vortex lattice. For the mixed dϩis-and d x 2 Ϫy 2ϩ id xy-wave pairing states, we observe a double-peak structure of the local density of states at vortex center, where the two peaks are asymmetrically situated around the Fermi energy. By taking into account the matrix-element effect, the local density of states appears to be qualitatively consistent with the scanningtunneling-microscopy experimental data.

Impurity-induced states in conventional and unconventional superconductors

“…The Kondo effect in these systems where the host single particle density of states follows a power law, has been studied intensively Hirschfeld, 1992, 1994;Bulla et al, 2000Bulla et al, , 1997Fradkin, 1996, 1997;Chen and Jayaprakash, 1995;Gonzalez-Buxton and Ingersent, 1998;Han et al, 2002Han et al, , 2004Ingersent, 1996;Ingersent and Si, 1998;Itoh, 1993;Logan and Glossop, 2000;Polkovnikov, 2002;Polkovnikov et al, 2001;Vojta and Bulla, 2001;Withoff and Fradkin, 1990;Zhang et al, 2001;Zhu and Ting, 2001a,b).…”

Impurity states ind-wave superconductors with a competing antiferromagnetic interaction

“…13 In this paper, we simply accept the existence of the magnetic moments as an experimental fact and will not address their microscopic formation.…”

“…In the PS model, the impurity spin is treated as a classical magnetic moment. On the other hand, different from the classical treatment of the impurity spin, several theoretical works [10][11][12][13] attributed the origin of the impurity state to the quantum spin dynamics of impurity-related magnetic moments. In other words, the degrees of freedom of impurity spin should be included and interact with the conduction electrons.…”

“…3 To examine the dominant mechanism of the impurity state, in a previous work 13 we studied the variation of the impurity resonance when a superconducting vortex with a normal metallic core was pinned right on the impurity site. However, the single LDOS peak associated with the vortex core in a normal metallic state of pure d-wave superconductors 15 has never been observed experimentally.…”

“…In other words, the degrees of freedom of impurity spin should be included and interact with the conduction electrons. For instance, according to the Anderson impurity (AI) model, 12,13 the internal degrees of freedom of the impurity are described by the Anderson d electrons, and the impurity interaction is expressed in real space as…”