0410075.pdf (345.12 kB)

The "normal" state of superconducting cuprates might really be normal after all

Download (345.12 kB)
preprint
posted on 03.04.2006, 17:13 by V.N. Zavaritsky, A.S. Alexandrov
High magnetic field studies of cuprate superconductors revealed a non-BCS temperature dependence of the upper critical field $H_{c2}(T)$ determined resistively by several groups. These determinations caused some doubts on the grounds of both the contrasting effect of the magnetic field on the in-plane and out-of-plane resistances reported for large Bi2212 sample and the large Nernst signal \emph{well above} $T_{c}$. Here we present both $\rho_{ab}(B)$ and $\rho_{c}(B)$ of tiny Bi2212 crystals in magnetic fields up to 50 Tesla. None of our measurements revealed a situation when on the field increase $\rho_c$ reaches its maximum while $\rho_{ab}$ remains very small if not zero. The resistive %upper critical fields estimated from the in-plane and out-of-plane $H_{c2}(T)$ estimated from $\rho_{ab}(B)$ and $\rho_{c}(B)$ are approximately the same. Our results support any theory of cuprates that describes the state above the resistive phase transition as perfectly normal with a zero off-diagonal order parameter. In particular, the anomalous Nernst effect above the resistive phase transition in high-$T_{c}$ cuprates can be described quantitatively as a normal state phenomenon in a model with itinerant and localised fermions and/or charged bosons.

History

School

  • Science

Department

  • Physics

Pages

353401 bytes

Publication date

2004

Notes

This is a pre-print. It is also available at: http://arxiv.org/abs/cond-mat/0410075.

Language

en

Exports

Logo branding

Exports