Funct. Mater. 2025; 32 (2): 190-193.

doi:https://doi.org/10.15407/fm32.02.190

Resistive investigation of pressure effect on the temperature dependence of the pseudogap in Y0.66Pr0.34Ba2Cu3O7-δsingle crystals accounting for the BCS - BEC crossover

G.Ya. Khadzhai1, I. Goulatis2, A. Chroneos2,3, V.M.P. Simoes1, R.V. Vovk 1

1 V.N. Karazin Kharkiv National University, 61022, Svoboda Sq. 4, Kharkiv, Ukraine
2Department of Electrical and Computer Engineering, University of Thessaly, 38334 Volos, Greece
3 Department of Materials, Imperial College London, London SW7 2BP, United Kingdom

Abstract: 

The effect of high hydrostatic pressure on the electrical conductivity, σ(Т), in the basal ab plane of the high-temperature superconductor (HTSC) Y0.66Pr0.34Ba2Cu3O7-δ single crystals was investigated. It was determined that excess conductivity Δσ(T) of the studied samples in a certain temperature range Tf < T < T* are characterized by a modified exponential temperature dependence Δσ ~ ( 1-T/T*)exp(Δ*ab/T), (T* is the mean field temperature of the superconducting transition), which is interpreted in terms of the BCS-BEC crossover theory. An increase in external pressure leads to a narrowing of the temperature range for the existence of a pseudogap (PG) regime, resulting an expansion of the linear temperature dependence of electrical resistivity in the basal ab plane.

Keywords: 
excess conductivity; doping; Y<sub>1-x</sub>Pr<sub>x</sub>Ba<sub>2</sub>Cu<sub>3</sub>O<sub>7-&delta;</sub> single crystals; high-temperature superconductivity; crossover; pseudogap state

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