Induced local spin-singlet amplitude and pseudogap in high-Tccuprates

Abstract

In this paper we show that local spin-singlet amplitude with d-wave symmetry, $〈|{\ensuremath{\Delta}}_{d}(0){|}^{2}〉,$ can be induced by short-range spin correlations even in the absence of pairing interactions. Fluctuation theory is formulated to make a connection between pseudogap temperature ${T}^{*},$ pseudogap size ${\ensuremath{\Delta}}_{\mathrm{pg}},$ and $〈|{\ensuremath{\Delta}}_{d}(0){|}^{2}〉.$ In the present scenario for the pseudogap, the normal-state pseudogap is caused by the induced local spin-singlet amplitude due to short-range spin correlations, which compete in the low-energy sector with superconducting correlations to make ${T}_{c}$ go to zero near half filling. Calculated ${T}^{*}$ falls from a high value onto the ${T}_{c}$ line and closely follows the mean-field N\'eel temperature ${T}_{N}^{\mathrm{MF}}.$ The calculated ${\ensuremath{\Delta}}_{\mathrm{pg}}$ is in good agreement with experimental results. We propose an experiment in which the present scenario can be critically tested.