Anisotropic ultrafast spin dynamics in epitaxial cobalt

Vivek Unikandanunni,Rajasekhar Medapalli,Karel Carva,Peter M Oppeneer,Eric E Fullerton,Stefano Bonetti

doi:10.1063/5.0049692

Abstract

We investigate the ultrafast spin dynamics in an epitaxial hcp(11¯00) cobalt thin film. By performing pump–probe magneto-optical measurements with the magnetization along either the easy or hard magnetic axis, we determine the demagnetization and recovery time for the two axes. We observe an average of 33% slower dynamics along the easy magnetization axis, which we attribute to magneto-crystalline anisotropy of the electron–phonon coupling, supported by our ab initio calculations. This points toward an unambiguous and previously undisclosed role of anisotropic electron–lattice coupling in ultrafast magnetism.

Highlights

The role of the lattice in ultrafast magnetism has been discussed since the early years following the pioneering experiment
We investigate the ultrafast spin dynamics in an epitaxial hcp(1100) cobalt thin film
We observe an average of 33% slower dynamics along the easy magnetization axis, which we attribute to magneto-crystalline anisotropy of the electron–phonon coupling, supported by our ab initio calculations

Summary

Introduction

The role of the lattice in ultrafast magnetism has been discussed since the early years following the pioneering experiment. By performing pump–probe magneto-optical measurements with the magnetization along either the easy or hard magnetic axis, we determine the demagnetization and recovery time for the two axes.

Results

Conclusion