Competing signatures of intersite and interlayer spin transfer in the ultrafast magnetization dynamics

TL;DR

This paper investigates how intersite and interlayer spin transfer processes compete to influence ultrafast magnetization dynamics in magnetic alloys, revealing that interlayer transfer can suppress the effects of intersite transfer and offering new control strategies.

Contribution

It demonstrates the competitive interplay between intersite and interlayer spin transfer in ultrafast magnetization, highlighting how interlayer transfer can dominate under certain conditions.

Findings

Intersite spin transfer dominates in the absence of interlayer transfer.

Interlayer spin transfer suppresses the influence of intersite transfer.

Control of magnetization dynamics can be achieved by tuning interlayer transfer.

Abstract

Optically driven intersite and interlayer spin transfer are individually known as the fastest processes for manipulating the spin order of magnetic materials on the sub 100 fs time scale. However, their competing influence on the ultrafast magnetization dynamics remains unexplored. In our work, we show that optically induced intersite spin transfer (also known as OISTR) dominates the ultrafast magnetization dynamics of ferromagnetic alloys such as Permalloy (Ni80Fe20) only in the absence of interlayer spin transfer into a substrate. Once interlayer spin transfer is possible, the influence of OISTR is significantly reduced and interlayer spin transfer dominates the ultrafast magnetization dynamics. This provides a new approach to control the magnetization dynamics of alloys on extremely short time scales by fine-tuning the interlayer spin transfer.