Superconductor-to-metal quantum phase transition in overdoped La2−xSrxCuO

Thomas R. Lemberger

¹

,

I. Hetel

²

,

A. Tsukada

³

et al.

Abstract

We investigate T c and magnetic penetration depth λ(T) near the superconductor-metal quantum phase transition in overdoped La 2-x Sr x CuO 4 films. Both T c and superfluid density n s ,  λ -2 , decrease with overdoping. They obey the scaling relation T c  [λ -2 (0)] α with α  ½. We discuss this result in the frameworks of disordered d-wave superconductors and of scaling near quantum critical points. Our result, and the linear scaling (α  1) found for the more anisotropic T 2 Ba 2 CuO 6+δ , can both be understood in terms of quantum critical scaling, with different dimensionalities for fluctuations.

Disorder and superfluid density in overdoped cuprate superconductors

“…[8][9][10] In addition, a variety of superconducting fluctuation effects have been observed above T c in underdoped cuprates. [11][12][13][14][15][16][17][18][19][20][21][22] On the overdoped side the situation is different: T c appears to closely track the energy gap, 9,10,23 as it would in a conventional superconductor; and, while the correlation between T c and ρ s remains, [24][25][26][27][28][29][30] the causal relationship between these quantities is far less clear. Complicating the chain of causality is another parameter -disorder -that directly influences ρ s , T c , and ∆ in a d-wave superconductor.…”

Universal linear-temperature resistivity: possible quantum diffusion transport in strongly correlated superconductors

“…Note that for superconducting thin films, the experimental magnetic penetration depth generally deviates from the London penetration depth λ L due to structural disorders in the films 28,29 . Even in high quality ultrathin films, there is a large difference in superfluid density between the film and the bulk materials with same T c 30,31 . Consequently all the data of the London penetration depth shown in Fig.…”

Locating the Missing Superconducting Electrons in the Overdoped Cuprates La2−xSrxCuO4Mahmood1, He2, Božović3 et al. 2019Phys. Rev. Lett.9120802View full textAdd to dashboardCite

“…While these observations imply that the normal state is conventional, it is an open question whether the superconducting state is conventional or not. Indeed, other studies indicate anomalies e.g., it has been found that the superfluid density was lower than expected as seen in different families of overdoped cuprates (e.g., Tl-2201 [5,6], Hg-1201 [7], Bi-2212 [8], La-214 [9][10][11][12]), and most recently shown comprehensively in overdoped La 2−x Sr x CuO 4 films [13].…”