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Dive into the research topics where Gregory Affeldt is active.

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Featured researches published by Gregory Affeldt.


Nature Communications | 2014

Ultrafast quenching of electron–boson interaction and superconducting gap in a cuprate superconductor

Wentao Zhang; Choongyu Hwang; Christopher Smallwood; Tristan Miller; Gregory Affeldt; Koshi Kurashima; Chris Jozwiak; H. Eisaki; T. Adachi; Yoji Koike; Dung-Hai Lee; Alessandra Lanzara

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.


Physical Review B | 2015

Influence of optically quenched superconductivity on quasiparticle relaxation rates in Bi 2 Sr 2 CaCu 2 O 8 + δ

Christopher Smallwood; Wentao Zhang; Tristan Miller; Gregory Affeldt; Koshi Kurashima; Chris Jozwiak; Takashi Noji; Yoji Koike; H. Eisaki; Dung-Hai Lee; Robert A. Kaindl; Alessandra Lanzara

We use time- and angle-resolved photoemission to measure quasiparticle relaxation dynamics across a laser-induced superconducting phase transition in Bi2Sr2CaCu2O8+delta. Whereas low-fluence measurements reveal picosecond dynamics, sharp femtosecond dynamics emerge at higher fluence. Analyses of data as a function of energy, momentum, and doping indicate that the closure of the near-nodal gap and disruption of macroscopic coherence are primary mechanisms driving this onset. The results demonstrate the important influence of transient electronic structure on relaxation dynamics, which is relevant for developing an understanding of nonequilibrium phase transitions.


Physical Review B | 2018

Doping-dependent correlation effects in ( Sr 1 − x La x ) 3 Ir 2 O 7

Gregory Affeldt; Tom Hogan; Jonathan D. Denlinger; Ashvin Vishwanath; Stephen D. Wilson; Alessandra Lanzara

Author(s): Affeldt, G; Hogan, T; Denlinger, JD; Vishwanath, A; Wilson, SD; Lanzara, A | Abstract:


Physical Review B | 2017

Spectral weight suppression near a metal-insulator transition in a double-layer electron-doped iridate

Gregory Affeldt; Tom Hogan; Christopher Smallwood; Tanmoy Das; Jonathan D. Denlinger; Stephen D. Wilson; Ashvin Vishwanath; Alessandra Lanzara


Journal of Electron Spectroscopy and Related Phenomena | 2014

Impact of work function induced electric fields on laser-based angle-resolved photoemission spectroscopy

A. Fero; Christopher Smallwood; Gregory Affeldt; Alessandra Lanzara


Bulletin of the American Physical Society | 2018

Electronic Structure Dynamics in Semimetallic TMD Mo 1-x W x Te 2 using Time- and Angle-Resolved Photoemission Spectroscopy

Conrad Stansbury; Nicholas Dale; Clara Nyby; Daniel Rhodes; Sam Ciocys; Gregory Affeldt; Aaron M. Lindenberg; Alessandra Lanzara


Bulletin of the American Physical Society | 2018

Study of nematicity in iron pnictide BaFe 2 (As 1-x P x ) 2 with micro-ARPES

Jonathan Ma; Gregory Affeldt; Ian Hayes; Chris Jozwiak; James G. Analytis; Alessandra Lanzara


Bulletin of the American Physical Society | 2017

Doping dependent correlation effects in (Sr

Gregory Affeldt; Tom Hogan; Jonathan D. Denlinger; Stephen Wilson; Alessandra Lanzara


Bulletin of the American Physical Society | 2016

_{1-x}

Alexander Nguyen; Gregory Affeldt; Kenneth Gotlieb; Alessandra Lanzara


Bulletin of the American Physical Society | 2016

La

Gregory Affeldt; Tom Hogan; Christopher Smallwood; Tanmoy Das; Jonathan D. Denlinger; Sung-Kwan Mo; Stephen Wilson; Alessandra Lanzara

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Alessandra Lanzara

Lawrence Berkeley National Laboratory

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Christopher Smallwood

Lawrence Berkeley National Laboratory

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Chris Jozwiak

Lawrence Berkeley National Laboratory

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Dung-Hai Lee

University of California

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Jonathan D. Denlinger

Lawrence Berkeley National Laboratory

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Tristan Miller

Lawrence Berkeley National Laboratory

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Wentao Zhang

Chinese Academy of Sciences

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H. Eisaki

National Institute of Advanced Industrial Science and Technology

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