Two-fluid model analysis of the terahertz conductivity of YBaCuO samples: optimally doped, underdoped and overdoped cases

Fuente: arXiv
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Main Authors: Šindler, Michal, Tzeng, Wen-Yen, Luo, Chih-Wei, Lin, Jiunn-Yuan, Kadlec, Christelle
Format: Preprint
Published: 2023
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author Šindler, Michal
Tzeng, Wen-Yen
Luo, Chih-Wei
Lin, Jiunn-Yuan
Kadlec, Christelle
author_facet Šindler, Michal
Tzeng, Wen-Yen
Luo, Chih-Wei
Lin, Jiunn-Yuan
Kadlec, Christelle
contents The complex conductivity of underdoped and optimally doped YBa$_2$Cu$_3$O$_{7-δ}$ samples and overdoped similar compound Y$_{0.7}$Ca$_{0.3}$Ba$_2$Cu$_3$O$_{7-δ}$ was measured using time-domain terahertz spectroscopy. In the normal state, the frequency dependence is described by the Drude model. Below the critical temperature $T_\mathrm{c}$, the two-fluid model was successfully employed to fit all the spectra, from 5 K up to $T_\mathrm{c}$. The temperature behaviour of fundamental parameters such as the scattering rate $1/τ$, the superfluid (normal) fraction $f_\mathrm{s}$ ($f_\mathrm{n}$) and the conductivity $σ$ was investigated at given frequencies. For the optimally doped and the overdoped samples, even at 5 K, a fifth of the electrons do not condense to the superfluid fraction. We observed that a substantial fraction of electrons do not condense to the superfluid fraction even at 5 K for optimally doped and overdoped samples. The real part of the conductivity $σ_1(T)$ exhibits a peak at low frequencies. It can be observed for all three stoichiometries and its exact shape depends on the quality of the sample. A further analysis shows that this peak is a consequence of the competition between the scattering time $τ(T)$ and the superfluid fraction $f_\mathrm{s}(T)$.
format Preprint
id arxiv_https___arxiv_org_abs_2309_17408
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Two-fluid model analysis of the terahertz conductivity of YBaCuO samples: optimally doped, underdoped and overdoped cases
Šindler, Michal
Tzeng, Wen-Yen
Luo, Chih-Wei
Lin, Jiunn-Yuan
Kadlec, Christelle
Superconductivity
The complex conductivity of underdoped and optimally doped YBa$_2$Cu$_3$O$_{7-δ}$ samples and overdoped similar compound Y$_{0.7}$Ca$_{0.3}$Ba$_2$Cu$_3$O$_{7-δ}$ was measured using time-domain terahertz spectroscopy. In the normal state, the frequency dependence is described by the Drude model. Below the critical temperature $T_\mathrm{c}$, the two-fluid model was successfully employed to fit all the spectra, from 5 K up to $T_\mathrm{c}$. The temperature behaviour of fundamental parameters such as the scattering rate $1/τ$, the superfluid (normal) fraction $f_\mathrm{s}$ ($f_\mathrm{n}$) and the conductivity $σ$ was investigated at given frequencies. For the optimally doped and the overdoped samples, even at 5 K, a fifth of the electrons do not condense to the superfluid fraction. We observed that a substantial fraction of electrons do not condense to the superfluid fraction even at 5 K for optimally doped and overdoped samples. The real part of the conductivity $σ_1(T)$ exhibits a peak at low frequencies. It can be observed for all three stoichiometries and its exact shape depends on the quality of the sample. A further analysis shows that this peak is a consequence of the competition between the scattering time $τ(T)$ and the superfluid fraction $f_\mathrm{s}(T)$.
title Two-fluid model analysis of the terahertz conductivity of YBaCuO samples: optimally doped, underdoped and overdoped cases
topic Superconductivity
url https://arxiv.org/abs/2309.17408