First-principles insights into all-optical spin switching in the half-metallic Heusler ferrimagnet Mn${}_2$RuGa

Abstract

All-optical spin switching (AOS) represents a new frontier in magnetic storage technology -- spin manipulation without a magnetic field, -- but its underlying working principle is not well understood. Many AOS ferrimagnets such as GdFeCo are amorphous and renders the high-level first-principles study unfeasible. The crystalline half-metallic Heusler Mn${}_2$RuGa presents an opportunity. Here we carry out hitherto the comprehensive density functional investigation into the material properties of Mn${}_2$RuGa, and introduce two concepts - the spin anchor site and the optical active site - as two pillars for AOS in ferrimagnets. In Mn${}_2$RuGa, Mn$(4a)$ serves as the spin anchor site, whose band structure is below the Fermi level and has a strong spin moment, while Mn$(4c)$ is the optical active site whose band crosses the Fermi level. Our magneto-optical Kerr spectrum and band structure calculation jointly reveal that the delicate competition between the Ru-$4d$ and Ga-$4p$ states is responsible for the creation of these two sites. These two sites found here not only present a unified picture for both Mn${}_2$RuGa and GdFeCo, but also open the door for the future applications. Specifically, we propose a Mn${}_2$Ru${}_x$Ga-based magnetic tunnel junction where a single laser pulse can control magnetoresistance.

21 pages, 3 figures, published on February 25, (2022). Supplementary materials provided at the publisher's link

References in corpus (10)

• All-optical control of ferromagnetic thin films and nanostructures
• Design of compensated ferrimagnetic Heusler alloys for giant tunable exchange bias
• Heusler 4.0: Tunable Materials
• Guidelines for understanding cubic manganese-rich Heusler compounds
• Compensated ferrimagnetic tetragonal Heusler thin films for antiferromagnetic spintronics
• Single shot all optical switching of intrinsic micron size magnetic domains of a Pt/Co/Pt ferromagnetic stack
• Switching ferromagnetic spins by an ultrafast laser pulse: Emergence of giant optical spin-orbit torque
• First-principles and model simulation of all-optical spin reversal
• Spin-orbit torque-mediated spin-wave excitation as an alternative paradigm for femtomagnetism
• Giant spin-orbit torque in a single ferrimagnetic metal layer