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

Amit Chanda; Christian Holzmann; Noah Schulz; Aladin Ullrich; Derick DeTellem; Manfred Albrecht; Miela Gross; Caroline A Ross; Dario A Arena; Manh-Huong Phan; Hariharan Srikanth

doi:10.1021/acsnano.3c12495

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

ACS Nano. 2024 Mar 5;18(9):7223-7240. doi: 10.1021/acsnano.3c12495. Epub 2024 Feb 23.

Affiliations

¹ Department of Physics, University of South Florida, Tampa, Florida 33620, United States.
² Institute of Physics, University of Augsburg, 86159 Augsburg, Germany.
³ Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.

PMID: 38394644
DOI: 10.1021/acsnano.3c12495

Abstract

The magnon propagation length, ⟨ξ⟩, of a ferro-/ferrimagnet (FM) is one of the key factors that controls the generation and propagation of thermally driven magnonic spin current in FM/heavy metal (HM) bilayer based spincaloritronic devices. For the development of a complete physical picture of thermally driven magnon transport in FM/HM bilayers over a wide temperature range, it is of utmost importance to understand the respective roles of temperature-dependent Gilbert damping (α) and effective magnetic anisotropy (K_eff) in controlling the temperature evolution of ⟨ξ⟩. Here, we report a comprehensive investigation of the temperature-dependent longitudinal spin Seebeck effect (LSSE), radio frequency transverse susceptibility, and broad-band ferromagnetic resonance measurements on Tm₃Fe₅O₁₂ (TmIG)/Pt bilayers grown on different substrates. We observe a significant drop in the LSSE voltage below 200 K independent of TmIG film thickness and substrate choice. This is attributed to the noticeable increases in effective magnetic anisotropy field, H_K^eff (∝K_eff) and α that occur within the same temperature range. From the TmIG thickness dependence of the LSSE voltage, we determined the temperature dependence of ⟨ξ⟩ and highlighted its correlation with the temperature-dependent H_K^eff and α in TmIG/Pt bilayers, which will be beneficial for the development of rare-earth iron garnet based efficient spincaloritronic nanodevices.

Keywords: Gilbert damping; inverse spin Hall effect; longitudinal spin Seebeck effect; magnetic anisotropy; magnon propagation length; rare-earth iron garnet.