Control of phase of the magnetization precession excited by circularly polarized fs-laser pulses

TL;DR

This paper demonstrates a method to control the phase of laser-excited magnetization precession in magnetic films by varying the laser incidence angle, offering a new tool for spintronic device manipulation.

Contribution

It introduces a novel approach to phase control of magnetization precession through incidence angle variation, supported by theoretical and experimental validation.

Findings

Phase increases with incidence angle, approximately proportional at small angles.

Experimental phase shift of about 4 degrees for a 15-degree change in incidence angle.

Provides a simple method for manipulating magnetization dynamics in spintronics.

Abstract

The inverse Faraday effect induced in magnetic films by ultrashort laser pulses allows excitation and control of spins at GHz and sub-THz frequencies. Frequency of the excited magnetization precession is easily tunable by the external magnetic field. On the other hand, phase of the precession hardly depends on magnetic field. Here we demonstrate an approach for the control of the precession phase by variation of the incidence angle of the laser pulses. In particular, theoretical consideration states that the phase increases with increase of the incidence angle and for small angles this relation is a direct proportionality. Experimental studies confirm this conclusion and provide shift of phase by about 4 deg. for the declination of the incidence angle by 15 deg. from the normal. This study provides a simple way for additional manipulation with optically excited magnetization dynamics, which is of importance for different spintronic applications.