Deterministic control of an antiferromagnetic spin arrangement using ultrafast optical excitation

Y W Windsor,D V Vyalikh,K Kummer,E V Chulkov,N Pontius,C Krellner,Ch Schüßler-Langeheine,A Ernst,K Kliemt,U Staub,L Rettig

doi:10.1038/s42005-020-00407-0

Abstract

A central prospect of antiferromagnetic spintronics is to exploit magnetic properties that are unavailable with ferromagnets. However, this poses the challenge of accessing such properties for readout and control. To this end, light-induced manipulation of the transient ground state, e.g. by changing the magnetic anisotropy potential, opens promising pathways towards ultrafast deterministic control of antiferromagnetism. Here, we use this approach to trigger a coherent rotation of the entire long-range antiferromagnetic spin arrangement about a crystalline axis in GdRh2Si2 and demonstrate deterministic control of this rotation. Our observations can be explained by a laser-induced shift of the direction of the Gd spins’ local magnetic anisotropy, and allow for a quantitative description of the transient magnetic anisotropy potential.

Highlights

A central prospect of antiferromagnetic spintronics is to exploit magnetic properties that are unavailable with ferromagnets
While in thermal equilibrium a number of approaches for control of AF spintronic systems have been demonstrated[2], more recently significant progress has been made in manipulating magnetism in AF and ferrimagnetic systems using ultrashort THz5–8 or visible[9,10] light pulses. Many of these approaches relied on very specific sample geometries or material properties, for example, non-centrosymmetric lattice symmetries[2,11]. Another possible route for control of antiferromagnetism using optical stimulation is to utilize the local anisotropy of the AF ordered ions to steer the magnetic state of a system
We found that Eq (1) provides a good description of the transient behaviours of φ(t) and m(t) (Fig. 4a, b). m(t) exhibits suppression and recovery dynamics, reminiscent of the ultrafast demagnetization dynamics found in various magnetic systems[21], while φ(t) exhibits a combination of a continuous rotation and a superimposed coherent oscillation, corresponding to a collective rotation of the entire AF structure upon photoexcitation (Fig. 3a)

Summary

Introduction

A central prospect of antiferromagnetic spintronics is to exploit magnetic properties that are unavailable with ferromagnets. A central advantage of antiferromagnetic (AF) over ferromagnetic (FM) spintronics arises from their selfcancelling spin arrangement with zero net moment, rendering them largely insensitive to external fields Such stability holds great potential for devices (e.g. for digital storage density and longevity), and poses significant challenges to implement magnetic functionality, requiring new approaches to interact with magnetic order. To this end, a key promise of AF spintronics is to exploit and control magnetic properties that are unique to antiferromagnets, such as the ordering wave vector or changes to the spin arrangement itself[2,3,4]. Further analysis of the coherent rotations of the AF structure allows us to fully determine the local magnetic anisotropy potential

Methods

Results

Conclusion