Ultrafast spin and heat transport after femtosecond pulsed laser excitation in metals

Student thesis: Master

Abstract

Ever since the discovery that the magnetization of a ferromagnetic thin film can be altered on sub-picosecond timescales, researchers have been putting a lot of effort into investigating this effect. However, many questions are still present on this subject. The main question addressed in this work is how transport of electrons influences these ultrafast magnetization dynamics.In this talk electron and heat transport are investigated on sub-picosecond timescales. This is done by measuring the influence of transport on the demagnetization of a magnetic material after heating by a short laser pulse.The main focus of this talk is the control of heat transport on ultrafast timescales using a so-called spin-valve geometry. The heat conduction of such a spin-valve can be altered using a magnetic field. The demagnetization of a magnetic layer placed on top of the spin-valve was then measured, and it has been unambiguously shown that the demagnetization is affected by this change in heat conduction. With this a proof of concept has been provided for the control of heat transport on these timescales, opening up new possibilities for future devices as a method to investigate the interplay between the charge and spin degrees of freedom on ultrafast timescales. Furthermore, simulations were done on the device using different models to describe heat transport, in search of the best way to describe transport on these short length- and timescales.
Date of Award31 Aug 2013
Original languageEnglish
SupervisorA.J. Schellekens (Supervisor 1) & Bert Koopmans (Supervisor 2)

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