Nernst Effect and Anomalous Transport in Cuprates: A Preformed-Pair Alternative to the Vortex Scenario

Abstract

We address those puzzling experiments in underdoped high $T_c$ superconductors which have been associated with normal state "vortices" and show these data can be understood as deriving from preformed pairs with onset temperature $T^{\ast }>T_c$. For uncorrelated bosons in small magnetic fields, and arbitrary $T^{\ast }/T_c$, we present the exact contribution to \textit{all} transport coefficients. In the overdoped regime our results reduce to those of standard fluctuation theories ($T^{\ast }\approx T_c$). Semi-quantitative agreement with Nernst, ac conductivity and diamagnetic measurements is quite reasonable.

9 pages, 4 figures; Title, abstract and contents modified, new references added, figures changed, one more figure added; to be published on PRB