Model of Preformed Hole-Pairs in c-Axis Transport in Cuprate Superconductors

Rana Janardan Singh

Department of Physics, Aligarh Muslim University, Aligarh, India..

DOI: 10.4236/wjcmp.2012.24039                

Abstract

Model of hole-pairs in electrical transport along ab plane in cuprate superconductors has already been proposed. It has been found to be in the shape of 3d_x2–y2 orbital of an electron in an atom. This time, model of hole-pairs in transport along c-axis in cuprate superconductors is proposed. In ab-plane, hole-pairs are formed along CuO₂ plane; one hole-pair covering 9 - 10 two dimensional CuO₂ unit cells in 3d_x2–y2 configuration. In the investigation of c-axis hole-pairs, cuprate superconductors have been sub-divided into three categories depending on the number of CuO₂ planes/formula unit. There is a little different treatment for finding out the order parameter in each category. Coherence lengths along ab-planes are of the order of a few tens of Angstroms, whereas along c-axis, they are less than even their a-, b-lattice constants. In cuprates with 2 or 3 CuO₂ planes, the order parameter is of 3d_z2–x2 type in zx-plane with lobes along both the axes much constrained. For cuprates with a single CuO₂ layer, the order parameter is of 3d_x2–y2 type, but its dimensions are less than a-, b-lattice constants.

Keywords

Cuprate Superconductors; Preformed Hole-Pairs; Electron Paramagnetic Resonance; 41 meV Peak in Neutron Diffraction

Conflicts of Interest

The authors declare no conflicts of interest.

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