Spin Flips versus Spin Transport in Nonthermal Electrons Excited by Ultrashort Optical Pulses in Transition Metals

V. Shokeen, M. Sanchez Piaia, J. Y. Bigot, T. Müller, P. Elliott, J. K. Dewhurst, S. Sharma, E. K.U. Gross

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67 Scopus citations

Abstract

A joint theoretical and experimental investigation is performed to understand the underlying physics of laser-induced demagnetization in Ni and Co films with varying thicknesses excited by 10 fs optical pulses. Experimentally, the dynamics of spins is studied by determining the time-dependent amplitude of the Voigt vector, retrieved from a full set of magnetic and nonmagnetic quantities performed on both sides of films, with absolute time reference. Theoretically, ab initio calculations are performed using time-dependent density functional theory. Overall, we demonstrate that spin-orbit induced spin flips are the most significant contributors with superdiffusive spin transport, which assumes only that the transport of majority spins without spin flips induced by scattering does not apply in Ni. In Co it plays a significant role during the first ∼20 fs only. Our study highlights the material dependent nature of the demagnetization during the process of thermalization of nonequilibrium spins.

Original languageAmerican English
Article number107203
JournalPhysical Review Letters
Volume119
Issue number10
DOIs
StatePublished - 8 Sep 2017
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2017 American Physical Society.

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