Magnon Diffusion Length and Longitudinal Spin Seebeck Effect in Vanadium Tetracyanoethylene (V[TCNE]$_x$, $x \sim 2$)

Seth W Kurfman; Denis R Candido; Brandi Wooten; Yuanhua Zheng; Michael J Newburger; Shuyu Cheng; Roland K Kawakami; Joseph P Heremans; Michael E Flatté; Ezekiel Johnston-Halperin

doi:10.48550/arxiv.2308.09752

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$Magnon Diffusion Length and Longitudinal Spin Seebeck Effect in Vanadium Tetracyanoethylene (V[TCNE]$_x$, $x \sim 2$)$

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Magnon Diffusion Length and Longitudinal Spin Seebeck Effect in Vanadium Tetracyanoethylene (V[TCNE]$_x$, $x \sim 2$)

Seth W Kurfman, Denis R Candido, Brandi Wooten, Yuanhua Zheng, Michael J Newburger, Shuyu Cheng, Roland K Kawakami, Joseph P Heremans, Michael E Flatté and Ezekiel Johnston-Halperin

ArXiv.org

08/18/2023

DOI: 10.48550/arxiv.2308.09752

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https://doi.org/10.48550/arxiv.2308.09752View

Preprint (Author's original)This preprint has not been evaluated by subject experts through peer review. Preprints may undergo extensive changes and/or become peer-reviewed journal articles. Open Access

Abstract

Spintronic, spin caloritronic, and magnonic phenomena arise from complex interactions between charge, spin, and structural degrees of freedom that are challenging to model and even more difficult to predict. This situation is compounded by the relative scarcity of magnetically-ordered materials with relevant functionality, leaving the field strongly constrained to work with a handful of well-studied systems that do not encompass the full phase space of phenomenology predicted by fundamental theory. Here we present an important advance in this coupled theory-experiment challenge, wherein we extend existing theories of the spin Seebeck effect (SSE) to explicitly include the temperature-dependence of magnon non-conserving processes. This expanded theory quantitatively describes the low-temperature behavior of SSE signals previously measured in the mainstay material yttrium iron garnet (YIG) and predicts a new regime for magnonic and spintronic materials that have low saturation magnetization, MS, and ultra-low damping. Finally, we validate this prediction by directly observing the spin Seebeck resistance (SSR) in the molecule-based ferrimagnetic semiconductor vanadium tetracyanoethylene (V[TCNE]x, x∼2). These results validate the expanded theory, yielding SSR signals comparable in magnitude to YIG and extracted magnon diffusion length (λm>1 μ m) and magnon lifetime for V[TCNE]x (τth≈1−10 μ s) exceeding YIG (τth∼10 ns). Surprisingly, these properties persist to room temperature despite relatively low spin wave stiffness (exchange). This identification of a new regime for highly efficient SSE-active materials opens the door to a new class of magnetic materials for spintronic and magnonic applications.

Physics - Materials Science

Details

Title: Subtitle: Magnon Diffusion Length and Longitudinal Spin Seebeck Effect in Vanadium Tetracyanoethylene (V[TCNE]$_x$, $x \sim 2$)
Creators: Seth W Kurfman
Denis R Candido
Brandi Wooten
Yuanhua Zheng
Michael J Newburger
Shuyu Cheng
Roland K Kawakami
Joseph P Heremans
Michael E Flatté
Ezekiel Johnston-Halperin
Resource Type: Preprint
Publication Details: ArXiv.org
DOI: 10.48550/arxiv.2308.09752
ISSN: 2331-8422
Language: English
Date posted: 08/18/2023
Academic Unit: Electrical and Computer Engineering; Physics and Astronomy
Record Identifier: 9984456076402771

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