Simultaneous suppression of superfluid and resistance on approach to superconductor-insulator transition in underdoped ultrathinCa0.3Y0.7Ba2Cu3

Abstract

Using simple four-terminal resistance measurements and two-coil superfluid stiffness measurements, we observe an extended temperature range wherein both the superfluid density and the resistance are substantially suppressed, in some cases below experimental resolution, in severely underdoped ultrathin films of Ca 0.3 Y 0.7 Ba 2 Cu 3 O 7−δ . This temperature range δ T c , deemed the 'offset', is in some films more than 1/2 of the resistive transition temperature. δ T c scales linearly with the characteristic two-dimensional vortex unbinding temperature T 2D , growing larger with underdoping upon approach to the superconductor-insulator transition. Absent in 3D samples of CaYBCO, we discuss the offset in the context of a previously observed 2D quantum critical point in the vicinity of the superconductor-insulator transition, as well as in the context of intrinsic and extrinsic inhomogeneities in the superconducting state of the film.

Nonmagnetic scattering induced suppression of superfluid density in Bi-2212

“…However, it is not clear whether any critical SPS is there beyond which increasing SPS is no more effective in controlling T c . The SPS is proportional to the superfluid density (σ s ) which is extracted in several superconducting systems [1][2][3][4][5][6][7][8][9][10]. Bi-2212 is such a superconducting 2D system in which SPS has been studied, the objective of which remains many [11][12][13][14].…”