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Heat Transport and Spin Accumulation in Nanoscale Metal Multilayers

  • Author(s): Gomez, Michael
  • Advisor(s): Wilson, Richard B
  • et al.
Abstract

The goal of this work is to understand spin and heat transfer in metal multilayer systems on nanoscale length scales and ultra-fast time scales due to ultra-fast laser pulse heating. Femto-second laser pulses are absorbed at the surface of the metal system. The absorbed energy is deposited in the metal’s electrons. Energy is then redistributed to vibrational and spin degrees of freedom through electron-electron, electron-phonon, and phonon-phonon interactions. Energy is also dispersed spatially through hot electron transport. The heat transfer in these metal systems can be divided into two temporal regimes with the first spanning from 0 to 1ps and the second from 1ps to 12.5ns

I present Time Domain Thermo-Reflectance (TDTR) and Time-Resolved Magneto Optic Kerr Effect (TR-MOKE) results that further our understanding of how heat is transported in these metal multilayer systems. By conducting various TDTR and TR-MOKE experiments, we are able to experimentally obtain fit parameters in order to prepare model predictions of the heat transfer in the metal systems. I also present my work on spin accumulation in Au due to the Spin dependent Seebeck Effect in Au-iron garnet bilayer systems. By varying the iron garnet used in the bilayer system, we are able to see how different magnetic insulators of the same family behave when demagnetized by ultra-fast laser pulses.

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