# Role of Spin Flips versus Spin Transport in Non Thermal Electrons Excited by Ultrashort Optical Pulses in Transition Metals

## TL;DR

This study combines theory and experiments to clarify the mechanisms behind laser-induced demagnetization in Ni and Co, showing spin-flips dominate over spin transport, with effects varying by material.

## Contribution

It provides a detailed analysis distinguishing the roles of spin-flips and spin transport in ultrafast demagnetization, emphasizing the dominance of spin-flips.

## Key findings

- Spin-flips are the primary mechanism in demagnetization.
- Super-diffusive spin transport has minimal impact.
- Demagnetization is material-dependent during thermalization.

## Abstract

A joint theoretical and experimental investigation is performed to understand the underlying physics of laser-induced demagnetization in Ni and Co films. Experimentally dynamics of spins is studied by determining the time-dependent amplitude of the Voigt vector and theoretically ab-initio calculations are performed using time-dependent density functional theory. We demonstrate that overall spin-orbit induced spin-flips are the most significant contributors with super-diffusive spin transport playing very limited to no role. Our study highlights the material dependent nature of the demagnetization during the process of thermalization of non-equilibrium spins.