Year: 2022
Type: article
Abstract: Recent study of overdoped ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4}$ cuprate superconductor thin films by Bo\ifmmode \check{z}\else \v{z}\fi{}ovi\ifmmode \acute{c}\else \'{c}\fi{} et al. has revealed several unexpected findings, most notably the violation of the BCS description which was believed to adequately describe overdoped cuprates. In particular, it was found that the superfluid density in ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4}$ films decreases on the overdoped side as a linear function of critical temperature ${T}_{c}$, which was taken as evidence for the violation of Homes' law. We show explicitly that the law is indeed violated, and as the main reason for violation we find that the superfluid density in Bo\ifmmode \check{z}\else \v{z}\fi{}ovi\ifmmode \acute{c}\else \'{c}\fi{}'s films is suppressed more strongly than in bulk samples. Based on the existing literature data, we show that the superfluid density in bulk cuprate samples does not decrease with doping, but instead tends to saturate on the overdoped side. The result is also supported by our recent measurement of a heavily overdoped bulk ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4}$ sample. Moreover, this saturation of superfluid density might not be limited to cuprates, as we find evidence for similar behavior in two pnictide superconductor families. We argue that quantum phase fluctuations play an important role in suppressing the superfluid density in thin films.
Authors: S. V. Dordevic, C. C. Homes
Institution: University of Akron
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W4283267408