Evidence for precursor superconducting pairing above T c in underdoped cuprates from an analysis of the in-plane infrared response

Šopík, B.; Chaloupka, Jiří; Dubroka, Adam; Bernhard, Christian; Munzar, Dominik

doi:10.1088/1367-2630/17/5/053022

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Journal article

Evidence for precursor superconducting pairing above T c in underdoped cuprates from an analysis of the in-plane infrared response

Šopík, B. Central European Institute of Technology, Masaryk University, Brno, Czech Republic
Chaloupka, Jiří Central European Institute of Technology, Masaryk University, Brno, Czech Republic
Dubroka, Adam Central European Institute of Technology, Masaryk University, Brno, Czech Republic - Department of Condensed Matter Physics, Faculty of Science, Masaryk University, Brno, Czech Republic
Bernhard, Christian University of Fribourg, Department of Physics and Fribourg Centre for Nanomaterials, Fribourg, Switzerland
Munzar, Dominik Central European Institute of Technology, Masaryk University, Brno, Czech Republic - Department of Condensed Matter Physics, Faculty of Science, Masaryk University, Brno, Czech Republic

15.05.2015

Published in:

New Journal of Physics. - 2015, vol. 17, no. 5, p. 053022

English We performed calculations of the in-plane infrared response of underdoped cuprate superconductors to clarify the origin of a characteristic dip feature which occurs in the published experimental spectra of the real part of the in-plane conductivity below an onset temperature ${{T}^{{\rm ons}}}$ considerably higher than ${{T}_{{\rm c}}}$. We provide several arguments, based on a detailed comparison of our results with the published experimental data, confirming that the dip feature and the related features of the memory function $M(\omega )={{M}_{1}}(\omega )+{\rm i}{{M}_{2}}(\omega )$ (a peak in M1 and a kink in M2) are due to superconducting pairing correlations that develop below ${{T}^{{\rm ons}}}$. In particular, we show that (i) the dip feature, the peak and the kink of the low-temperature experimental data can be almost quantitatively reproduced by calculations based on a model of a d-wave superconductor. The formation of the dip feature in the experimental data below ${{T}^{{\rm ons}}}$ is shown to be analogous to the one occurring in the model spetra below ${{T}_{{\rm c}}}$. (ii) Calculations based on simple models, for which the dip in the temperature range from ${{T}_{{\rm c}}}$ to ${{T}^{{\rm ons}}}$ is unrelated to superconducting pairing, predict a shift of the onset of the dip at the high-energy side upon entering the superconducting state, that is not observed in the experimental data; (iii) the conductivity data in conjunction with the recent photoemission data (Reber et al 2012 Nat. Phys. 8 606, Reber et al 2013 Phys. Rev. B 87 060506) imply the persistence of the coherence factor characteristic of superconducting pairing correlations in a range of temperatures above ${{T}_{{\rm c}}}$.

Faculty

Faculté des sciences et de médecine

Department

Département de Physique

Language