title: Photoinduced melting of antiferromagnetic order in La(0.5)Sr(1.5)MnO4 measured using ultrafast resonant soft x-ray diffraction.
abstract: We used ultrafast resonant soft x-ray diffraction to probe the picosecond dynamics of spin and orbital order in La(0.5)Sr(1.5)MnO(4) after photoexcitation with a femtosecond pulse of 1.5 eV radiation. Complete melting of antiferromagnetic spin order is evidenced by the disappearance of a (1/4,1/4,1/2) diffraction peak. On the other hand, the (1/4,1/4,0) diffraction peak, reflecting orbital order, is only partially reduced. We interpret the results as evidence of destabilization in the short-range exchange pattern with no significant relaxation of the long-range Jahn-Teller distortions. Cluster calculations are used to analyze different possible magnetically ordered states in the long-lived metastable phase. Nonthermal coupling between light and magnetism emerges as a primary aspect of photoinduced phase transitions in manganites.
authors.affiliation: Department of Physics, Clarendon Laboratory, University of Oxford, Oxford, United Kingdom.
authors.forename: H
authors.initials: H
authors.lastname: Ehrke
authors.forename: R I
authors.initials: RI
authors.lastname: Tobey
authors.forename: S
authors.initials: S
authors.lastname: Wall
authors.forename: S A
authors.initials: SA
authors.lastname: Cavill
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authors.lastname: Först
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authors.lastname: Khanna
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authors.lastname: Garl
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authors.lastname: Stojanovic
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authors.initials: D
authors.lastname: Prabhakaran
authors.forename: A T
authors.initials: AT
authors.lastname: Boothroyd
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authors.lastname: Gensch
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authors.lastname: Mirone
authors.forename: P
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authors.lastname: Reutler
authors.forename: A
authors.initials: A
authors.lastname: Revcolevschi
authors.forename: S S
authors.initials: SS
authors.lastname: Dhesi
authors.forename: A
authors.initials: A
authors.lastname: Cavalleri