Classical limit of Rabi nutations in spins of ferromagnets

TL;DR

This paper reports the observation of classical Rabi nutations in ferromagnetic spins, achieved through laser and microwave techniques, highlighting potential for phase-coherent spin control in magnetic materials.

Contribution

It demonstrates the classical Rabi nutations in ferromagnets and introduces a method to extend coherence times for spin manipulation.

Findings

Resonant spins exhibit extended coherence times.

Gilbert damping enhances relaxation times.

First observation of classical Rabi nutations in ferromagnets.

Abstract

Rabi oscillations describe the interaction of a two-level system with a rotating electromagnetic field. As such, they serve as the principle method for manipulating quantum bits. By using a combination of femtosecond laser pulses and microwave excitations, we have observed the classical form of Rabi nutations in a ferromagnetic system whose equations of motion mirror the case of a precessing quantum two-level system. Key to our experiments is the selection of a subset of spins that is in resonance with the microwave excitation and whose coherence time is thereby extended. Taking advantage of Gilbert damping, the relaxation times are further increased such that mode-locking takes place. The observation of such Rabi nutations is the first step towards potential applications based on phase-coherent spin manipulation in ferromagnets.