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Correlating quasiparticle excitations with quantum femtosecond magnetism in photoexcited nonequilibrium states of insulating antiferromagnetic manganites

TitleCorrelating quasiparticle excitations with quantum femtosecond magnetism in photoexcited nonequilibrium states of insulating antiferromagnetic manganites
Publication TypeJournal Article
Year of Publication2017
AuthorsLingos, PC, Patz, A, Li, T, Barmparis, GD, Keliri, A, Kapetanakis, MD, Li, L, Yan, J, Wang, J, Perakis, IE
JournalPhysical Review B
Volume95
Pagination224432
Date Published06
Type of ArticleArticle
ISBN Number2469-9950
Accession NumberWOS:000404467000002
Keywordscharge, double exchange, dynamics, order, phase, physics, semiconductors, separation, transition, vo2
Abstract

We describe a mechanism for insulator-to-metal transition triggered by spin canting following femtosecond laser excitation of insulating antiferromagnetic (AFM) states of colossal magnetoresistive (CMR) manganites. We show that photoexcitation of composite fermion quasiparticles dressed by spin fluctuations results in the population of a broad metallic conduction band due to canting of the AFM background spins via strong electron-spin local correlation. By inducing spin canting, photoexcitation can increase the quasiparticle energy dispersion and quench the charge excitation energy gap. This increases the critical Jahn-Teller (JT) lattice displacement required to maintain an insulating state. We present femtosecond-resolved pump-probe measurements showing biexponential relaxation of the differential reflectivity below the AFM transition temperature. We observe a nonlinear dependence of the ratio of the femtosecond and picosecond relaxation component amplitudes at the same pump fluence threshold where we observe femtosecond magnetization photoexcitation. We attribute this correlation between nonlinear femtosecond spin and charge dynamics to spin/charge/lattice coupling and population inversion between the polaronic majority carriers and metallic quasielectron minority carriers as the lattice displacement becomes smaller than the critical value required to maintain an insulating state following laser-induced spin canting.

DOI10.1103/PhysRevB.95.224432
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