Abstract
Many high-Tc superconductors, Iron-based superconductors, and other recently discovered superconducting materials show the signature of the existence of a strange Pseudo Gap above the superconducting transition temperature. Various experimental techniques such as NMR, Tunneling, and ARPES suggest that the pseudo gap does not change with temperature. As evidenced by these experimental results, the Pseudo gap possesses a d-wave pairing symmetry similar to the superconducting energy gap. The physical properties show unusual behavior in the non-superconducting state where a pseudo gap exists. Based on experimental evidence we argue about the origin of the pseudo gap in these superconductors. Although a complete understanding of the mechanism is lacking, the existence of preformed cooper indicated by various experimental probe pairs seems to be responsible for the origin of the Pseudo gap.
Keywords: Pseudo Gap, Unconventional Superconductors,
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