Optically controlling the competition between spin flips and intersite spin transfer in a Heusler half-metal on sub-100-fs time scales

Sinéad A Ryan; Peter C Johnsen; Mohamed F Elhanoty; Anya Grafov; Na Li; Anna Delin; Anastasios Markou; Edouard Lesne; Claudia Felser; Olle Eriksson; Henry C Kapteyn; Oscar Grånäs; Margaret M Murnane

doi:10.1126/sciadv.adi1428

Optically controlling the competition between spin flips and intersite spin transfer in a Heusler half-metal on sub-100-fs time scales

Sci Adv. 2023 Nov 10;9(45):eadi1428. doi: 10.1126/sciadv.adi1428. Epub 2023 Nov 10.

Authors

Sinéad A Ryan¹, Peter C Johnsen¹, Mohamed F Elhanoty², Anya Grafov¹, Na Li¹, Anna Delin^{3

4

5}, Anastasios Markou^{6

7}, Edouard Lesne⁷, Claudia Felser⁷, Olle Eriksson^{2

5}, Henry C Kapteyn^{1

8}, Oscar Grånäs², Margaret M Murnane¹

Affiliations

¹ JILA, University of Colorado Boulder, 440 UCB, Boulder, CO 80309, USA.
² Division of Materials Theory, Department of Physics and Astronomy, Uppsala University, Box-516, SE 75120, Sweden.
³ Department of Applied Physics, School of Engineering Sciences, KTH Royal Institute of Technology, AlbaNova University Center, SE-10691 Stockholm, Sweden.
⁴ Swedish e-Science Research Center (SeRC), KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden.
⁵ Wallenberg Initiative Materials Science for Sustainability, Uppsala University, 75121 Uppsala, Sweden.
⁶ Physics Department, University of Ioannina, 45110 Ioannina, Greece.
⁷ Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany.
⁸ KMLabs Inc., Boulder, CO 80301, USA.

Abstract

The direct manipulation of spins via light may provide a path toward ultrafast energy-efficient devices. However, distinguishing the microscopic processes that can occur during ultrafast laser excitation in magnetic alloys is challenging. Here, we study the Heusler compound Co₂MnGa, a material that exhibits very strong light-induced spin transfers across the entire M-edge. By combining the element specificity of extreme ultraviolet high-harmonic probes with time-dependent density functional theory, we disentangle the competition between three ultrafast light-induced processes that occur in Co₂MnGa: same-site Co-Co spin transfer, intersite Co-Mn spin transfer, and ultrafast spin flips mediated by spin-orbit coupling. By measuring the dynamic magnetic asymmetry across the entire M-edges of the two magnetic sublattices involved, we uncover the relative dominance of these processes at different probe energy regions and times during the laser pulse. Our combined approach enables a comprehensive microscopic interpretation of laser-induced magnetization dynamics on time scales shorter than 100 femtoseconds.