Quantum critical behaviour in the superfluid density of strongly underdoped ultrathin cuprate films

Abstract

A central issue in the physics of high temperature superconductors is to understand superconductivity within a single copper-oxide layer or bilayer, the fundamental structural unit in the cuprates, and how it is lost with underdoping. As mobile holes are removed from the CuO_2 planes, the transition temperature T_C and superfluid density n_S decrease in a surprisingly correlated fashion in crystals and thick films. We seek to elucidate the intrinsic physics of bilayers in the strongly underdoped regime, near the critical doping level where superconductivity disappears. We report measurements of n_S(T) in films of Y_{1-x}Ca_xBa_2Cu_3O_{7-δ} as thin as two copper-oxide bilayers with T_C's as low as 3 K. In addition to seeing the two-dimensional (2D) Kosterlitz-Thouless-Berezinski transition at T_C, we observe a remarkable scaling of T_C with n_S(0) that demonstrates that the disappearance of superconductivity with underdoping is due to quantum fluctuations near a T = 0 2D quantum critical point.

13 pages, 2 figure

References in corpus (4)

• Criticality in correlated quantum matter
• Scaling of the superfluid density in high-temperature superconductors
• 4D-XY quantum criticality in a doped Mott insulator
• The Role of Thermal Phase Fluctuations in Underdoped YBCO Films

Cited by in corpus (7)

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• Restoration of the magnetic hc/e-periodicity in unconventional superconductors
• Doping dependence of the vortex-core energy in bilayer films of cuprates
• Giant proximity effect in a phase-fluctuating superconductor
• Tuning the interlayer spacing in high T_c superconductors: penetration depth and two-dimensional superfluid density
• ARPES, Neutrons, and the High-$T_c$ Mechanism
• Biot-Savart correlations in layered superconductors