Magnon-mediated spin currents in Tm3Fe5O12/Pt with perpendicular magnetic anisotropy

TL;DR

This paper explores magnon-mediated spin currents in Tm3Fe5O12/Pt bilayers with perpendicular magnetic anisotropy, demonstrating efficient spin-to-charge conversion and potential for spintronic memory devices.

Contribution

It provides experimental insights into magnon-driven spin currents in garnet films with PMA, highlighting their suitability for spintronic applications.

Findings

High spin Seebeck coefficient of 0.54 μV/K

Low Gilbert damping constant (~0.01)

Effective spin-to-charge conversion observed

Abstract

The control of pure spin currents carried by magnons in magnetic insulator (MI) garnet films with a robust perpendicular magnetic anisotropy (PMA) is of great interest to spintronic technology as they can be used to carry, transport and process information. Garnet films with PMA present labyrinth domain magnetic structures that enrich the magnetization dynamics, and could be employed in more efficient wave-based logic and memory computing devices. In MI/NM bilayers, where NM being a normal metal providing a strong spin-orbit coupling, the PMA benefits the spin-orbit torque (SOT) driven magnetization's switching by lowering the needed current and rendering the process faster, crucial for developing magnetic random-access memories (SOT-MRAM). In this work, we investigated the magnetic anisotropies in thulium iron garnet (TIG) films with PMA via ferromagnetic resonance measurements, followed by the excitation and detection of magnon-mediated pure spin currents in TIG/Pt driven by microwaves and heat currents. TIG films presented a Gilbert damping constant {\alpha}~0.01, with resonance fields above 3.5 kOe and half linewidths broader than 60 Oe, at 300 K and 9.5 GHz. The spin-to-charge current conversion through TIG/Pt was observed as a micro-voltage generated at the edges of the Pt film. The obtained spin Seebeck coefficient was 0.54 {\mu}V/K, confirming also the high interfacial spin transparency.