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

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 have 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/non-magnetic (NM) bilayers, where NM is a normal metal providing a strong spin–orbit coupling, the PMA benefits the spin–orbit torque-driven magnetization switching by lowering the needed current and rendering the process faster, crucial for developing magnetic random-access memories. 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 of α ≈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 microvoltage generated at the edges of the Pt film. The obtained spin Seebeck coefficient was 0.54 μV/K, also confirming the high interfacial spin transparency.

Temperature Evolution of Magnon Propagation Length in Tm3Fe5O12 Thin Films: Roles of Magnetic Anisotropy and Gilbert Damping

“…This is why the YIG thin films also do not show any low field anomalous feature in the V ISHE ( H ) loops . Additionally, the V ISHE ( H ) loop for our TmIG film with PMA (the 28 nm film) at 295 K is quite similar to that of a TmIG thin film with PMA at room temperature reported in the literature . In Figure c,d, we demonstrate the T -dependence of the background-corrected LSSE voltage V L S S E false( T false) = V I S H E false( T , prefix+ μ 0 H normals normala normalt false) − V I S H E false( T , prefix− μ 0 H normals normala normalt false) 2 for Δ T = +10 K on the left y -scale and corresponding M S ( T ) on the right y -scale for GSGG/TmIG(236 nm)/Pt(5 nm) and GSGG/TmIG(28 nm)/Pt(5 nm), respectively.…”

“…44,45 Recently, the LSSE has been investigated in TmIG/Pt bilayers with PMA at room temperature and shown to exhibit high interfacial spin transparency and spin-to-charge conversion efficiency at the TmIG/Pt interface. 46 TmIG has a higher Gilbert damping parameter (∼10 −2 ) 6 compared to YIG, and unlike GdIG, TmIG does not exhibit any magnetic compensation in the temperature range between 1.5 and 300 K, 47,48 which allows us to probe the relative contribution of α toward the temperature evolution of ⟨ξ⟩ and hence the LSSE over a broad temperature range close to room temperature. However, the temperature evolution of LSSE and hence ⟨ξ⟩ as well as their relationship with α and K eff in TmIG/Pt bilayers have yet to be explored, which would be of critical importance for REIG-based efficient magnonic device applications.…”

Large Thermo-Spin Effects in Heusler Alloy-Based Spin Gapless Semiconductor Thin Films

“…In Figure e, we compare α( T ) for theMgO/CoFeCrGa (95 nm) and MgO/CoFeCrGa (95 nm)/Pt (5 nm) films. It is evident that α CoFeCrGa/Pt > α CoFeCrGa at all the temperatures, and both α CoFeCrGa/Pt and α CoFeCrGa increase with decreased temperature, especially below 225 K. Such increase in α and Δ H at low temperatures can be primarily attributed to the impurity relaxation mechanisms. − Since ξ ∝ 1 α , an increase in α at low temperatures gives rise to a decrease in ⟨ξ⟩ and hence the LSSE signal.…”

Fast All-Electron Hybrid Functionals and Their Application to Rare-Earth Iron Garnets

“…As two representatives of the rare-earth-iron garnet group, we chose to examine Gd 3 Fe 5 O 12 (GdIG) and Tm 3 Fe 5 O 12 (TmIG) more closely. We selected these materials, because a lot of interesting experimental (Fechine et al, 2008;Phan et al, 2009;Lassri et al, 2011;Lee et al, 2020;Vilela et al, 2020;Vu et al, 2020) and even some theoretical work using the FLAPW method (Lassri et al, 2011) has been published for these materials.…”