title: Ultrafast quenching of electron-boson interaction and superconducting gap in a cuprate superconductor.
abstract: Ultrafast spectroscopy is an emerging technique with great promise in the study of quantum materials, as it makes it possible to track similarities and correlations that are not evident near equilibrium. Thus far, however, the way in which these processes modify the electron self-energy--a fundamental quantity describing many-body interactions in a material--has been little discussed. Here we use time- and angle-resolved photoemission to directly measure the ultrafast response of self-energy to near-infrared photoexcitation in high-temperature cuprate superconductor. Below the critical temperature of the superconductor, ultrafast excitations trigger a synchronous decrease of electron self-energy and superconducting gap, culminating in a saturation in the weakening of electron-boson coupling when the superconducting gap is fully quenched. In contrast, electron-boson coupling is unresponsive to ultrafast excitations above the critical temperature of the superconductor and in the metallic state of a related material. These findings open a new pathway for studying transient self-energy and correlation effects in solids.
authors.affiliation: 1] Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [2] Department of Physics, University of California Berkeley, Berkeley, California 94720, USA.
authors.forename: Wentao
authors.initials: W
authors.lastname: Zhang
authors.affiliation: 1] Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [2] Department of Physics, Pusan National University, Busan 609-735, Republic of Korea.
authors.forename: Choongyu
authors.initials: C
authors.lastname: Hwang
authors.affiliation: 1] Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [2] Department of Physics, University of California Berkeley, Berkeley, California 94720, USA.
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Smallwood
authors.affiliation: 1] Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [2] Department of Physics, University of California Berkeley, Berkeley, California 94720, USA.
authors.forename: Tristan L
authors.initials: TL
authors.lastname: Miller
authors.affiliation: 1] Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [2] Department of Physics, University of California Berkeley, Berkeley, California 94720, USA.
authors.forename: Gregory
authors.initials: G
authors.lastname: Affeldt
authors.affiliation: Department of Applied Physics, Tohoku University, Sendai 980-8579, Japan.
authors.forename: Koshi
authors.initials: K
authors.lastname: Kurashima
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Chris
authors.initials: C
authors.lastname: Jozwiak
authors.affiliation: Electronics and Photonics Research Institute, National Institute of Advanced Industrial Science and Technology, Ibaraki 305-8568, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Eisaki
authors.affiliation: 1] Department of Applied Physics, Tohoku University, Sendai 980-8579, Japan [2] Department of Engineering and Applied Sciences, Sophia University, Tokyo 102-8554, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Adachi
authors.affiliation: Department of Applied Physics, Tohoku University, Sendai 980-8579, Japan.
authors.forename: Yoji
authors.initials: Y
authors.lastname: Koike
authors.affiliation: Department of Physics, University of California Berkeley, Berkeley, California 94720, USA.
authors.forename: Dung-Hai
authors.initials: DH
authors.lastname: Lee
authors.affiliation: 1] Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [2] Department of Physics, University of California Berkeley, Berkeley, California 94720, USA.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Lanzara