Publication Date:
2016-12-29
Description:
Author(s): Emrah Turgut, Dmitriy Zusin, Dominik Legut, Karel Carva, Ronny Knut, Justin M. Shaw, Cong Chen, Zhensheng Tao, Hans T. Nembach, Thomas J. Silva, Stefan Mathias, Martin Aeschlimann, Peter M. Oppeneer, Henry C. Kapteyn, Margaret M. Murnane, and Patrik Grychtol The excitation of a ferromagnetic film by a femtosecond laser pulse causes an unexpectedly fast quenching of the film’s magnetization on subpicosecond time scales. The microscopic physical mechanisms responsible for this remain a scientific puzzle. The authors employ femtosecond extreme ultraviolet pulses produced by high harmonic generation to follow how the magnetization of a thin cobalt film evolves after the excitation by a 40-fs laser pulse. By measuring the time-, energy-, and angle-resolved magneto-optical response of the Co films across the M 2 , 3 absorption edge, they obtain a set of time-lapsed magnetic asymmetry spectra, which contain a wealth of information about the different mechanisms at work. When combined with advanced ab initio magneto-optical calculations, they identify two dominant contributions: first, a transient reduction of exchange splitting, and second, magnon excitation. This work thus distinguishes between two fundamental models of magnetism, the Stoner and Heisenberg models, which ascribe magnetization dynamics to an exchange splitting reduction and spin wave excitations, respectively. [Phys. Rev. B 94, 220408(R)] Published Wed Dec 28, 2016
Keywords:
Magnetism
Print ISSN:
1098-0121
Electronic ISSN:
1095-3795
Topics:
Physics
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