Shining light on spintronics: unlocking an elementary interaction between light and magnetism using insights from Spintronics and Quantum technologies

by Prof. Amir Capua

Applied Physics at the Hebrew University of Jerusalem

at Condensed Matter Seminar

Mon, 02 Dec 2024, 11:10
Sacta-Rashi Building for Physics (54), room 207

Abstract

The magnetic component of light is usually neglected when considering light-matter interactions. This is because the force that acts on the dipoles which originates from the electrical field is orders of magnitude stronger than the Lorentz force. On the other hand, for typical fields, ferromagnetic resonance (FMR) typically on Gigahertz timescales. Therefore, it seems unlikely that optical magnetic fields that oscillate at ∼ 400 − 800 THz may interact with magnetic moments.
However, by combining principles from quantum optics, we have recently realized that the equations governing the FMR experiment are relevant even for magnetic fields that oscillate much faster, at optical frequencies. Namely, the interaction between optical beams and the magnetization is made possible. We find that the strength of the interaction is determined by an elementary efficiency parameter η=αγH/f_opt, where H is the amplitude of the optical magnetic field, α is the dissipation rate of spin angular momentum to the lattice, and f_opt and γ are the optical frequency and gyromagnetic ratio.
Our results shed light on a variety of highly debated experimental observations on the interaction between optical fields and ferromagnets that have been reported in the last 25 years.

Created on 25-11-2024 by Naamneh, Muntaser (mnaamneh)
Updaded on 25-11-2024 by Naamneh, Muntaser (mnaamneh)