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Critical speeding up of nonequilibrium electronic relaxation near nematic phase transition in unstrained Ba(Fe1-xCox)(2)As-2

TitleCritical speeding up of nonequilibrium electronic relaxation near nematic phase transition in unstrained Ba(Fe1-xCox)(2)As-2
Publication TypeJournal Article
Year of Publication2017
AuthorsPatz, A, Li, T, Luo, L, Yang, X, Bud'ko, SL, Canfield, PC, Perakis, IE, Wang, J
JournalPhysical Review B
Volume95
Pagination165122
Date Published04
Type of ArticleArticle
ISBN Number2469-9950
Accession NumberWOS:000400783900006
Keywordsbafe2as2, order, physics, state, superconductor
Abstract

Ising, Z(2), symmetry breaking. Here we use a strain- and stress-free twinned sample to show that there is a significant reduction in the energy relaxation times of the hot electrons following nonequilibrium femtosecond laser excitation on both the high- and low-temperature sides of the nematic phase transition. This femtosecond critical speeding-up behavior provides an alternative way to study complex, electronically driven nematicity, neither invoking external strain nor measuring a small anisotropy in twinned crystals. Particularly, a detailed analysis of the observed ultrafast decay time and the amplitude associated with an initial electronic relaxation provides compelling implications on the physical origin of nematicity in iron pnictides: (1) nematic fluctuations strongly influence the dynamics of electron cooling, and (2) spin fluctuations determine the part of amplitude arising from the nematicity. Finally, we discuss ultrafast coherent phonon generation which may contribute to the measured transition temperature in our ultrafast measurements.

DOI10.1103/PhysRevB.95.165122
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Complex States

Alternate JournalPhys. Rev. B