Quasi-particles ultrafastly releasing kink bosons to form Fermi arcs in a cuprate superconductor

TL;DR

This study demonstrates that ultrafast laser pulses can cause quasi-particles in a cuprate superconductor to undress from kink bosons, leading to the formation of Fermi arcs and shedding light on the loss of superconductivity at T_c.

Contribution

It provides experimental evidence linking the undressing of quasi-particles from kink bosons to the emergence of Fermi arcs and the loss of superconductivity in high-T_c cuprates, challenging conventional theories.

Findings

Ultrafast laser pulses induce Fermi arcs in cuprates.

Spectral broadening occurs within the kink binding energy.

Loss of superconducting gap correlates with quasi-particle undressing.

Abstract

In a conventional framework, superconductivity is lost at a critical temperature (T_c) because, at higher temperatures, gluing bosons can no longer bind two electrons into a Cooper pair. In high-T_c cuprates, it is still unknown how superconductivity vanishes at T_c. We provide evidence that the so-called <~70-meV kink bosons that dress the quasi-particle excitations are playing a key role in the loss of superconductivity in a cuprate. We irradiated a 170-fs laser pulse on Bi2Sr2CaCu2O8+\delta and monitored the responses of the superconducting gap and dressed quasi-particles by time- and angle-resolved photoemission spectroscopy. We observe an ultrafast loss of superconducting gap near the d-wave node, or light-induced Fermi arcs, which is accompanied by spectral broadenings and weight redistributions occurring within the kink binding energy. We discuss that the underlying mechanism of the spectral broadening that induce the Fermi arc is the undressing of quasi-particles from the kink bosons. The loss mechanism is beyond the conventional framework, and can accept the unconventional phenomena such as the signatures of Cooper pairs remaining at temperatures above T_c.