The electronic structure of Bi2Sr2CaCu2Oy in the presence of a super-current: Flux-flow, Doppler shift and quasiparticle pockets

M Naamneh, JC Campuzano, A Kanigel

Research output: Working paper/PreprintPreprint

Abstract

There are several ways to turn a superconductor into a normal conductor: increase the temperature, apply a high magnetic field, or run a large current. High-Tc cuprate superconductors are unusual in the sense that experiments suggest that destroying superconductivity by heating the sample to temperatures above Tc or by applying a high magnetic field result in different ’normal’ states. Spectroscopic probes show that above Tc, in the pseudogap regime, the Fermi surface is partly gapped and there are no well-defined quasiparticles. Transport measurements, on the contrary, reveal quantum oscillations in high magnetic fields and at low temperatures, suggesting a more
usual Fermi liquid state. Studying the electronic structure while suppressing superconductivity by using current, will hopefully shed new light on this problem. In type II superconductors, such as the cuprates, the resistive state created by the current is a result of vortex motion. The large dissipation in the flux-flow regime makes spectroscopic measurements in the presence of current challenging. We performed angle-resolved photoemission experiments in thin films of Bi2Sr2CaCu2Oy while running high-density current through the samples. Clear evidence was found for non-uniform flux flow, leaving most of the sample volume free of mobile vortices and dissipation. The super-current changes the electronic spectrum, creating quasiparticle and quasihole pockets. The size of these pockets as a function of the current is found to be doping dependent; it depends both on the superfluid stiffness and on the strength of interactions.
Original languageEnglish
StatePublished - 2016

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