The challenges of measuring spin Seebeck noise

Fuente: arXiv
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Autori principali: Luo, Renjie, Zhao, Xuanhan, Legvold, Tanner J., Chen, Liyang, Liu, Changjiang, Hong, Deshun, Bhattacharya, Anand, Natelson, Douglas
Natura: Preprint
Pubblicazione: 2023
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author Luo, Renjie
Zhao, Xuanhan
Legvold, Tanner J.
Chen, Liyang
Liu, Changjiang
Hong, Deshun
Bhattacharya, Anand
Natelson, Douglas
author_facet Luo, Renjie
Zhao, Xuanhan
Legvold, Tanner J.
Chen, Liyang
Liu, Changjiang
Hong, Deshun
Bhattacharya, Anand
Natelson, Douglas
contents Just as electronic shot noise in driven conductors results from the granularity of charge and the statistical variation in the arrival times of charge carriers, there are predictions for fundamental noise in magnon currents due to angular momentum being carried by discrete excitations. The inverse spin Hall effect as a transduction mechanism to convert spin current into charge current raises the prospect of experimental investigations of such magnon shot noise. Spin Seebeck effect measurements have demonstrated the electrical detection of thermally driven magnon currents and have been suggested as an avenue for accessing spin current fluctuations. Using spin Seebeck structures made from yttrium iron garnet on gadolinium gallium garnet, we demonstrate the technical challenges inherent in such noise measurements. While there is a small increase in voltage noise in the inverse spin Hall detector at low temperatures associated with adding a magnetic field, the dependence on field orientation implies that this is not due to magnon shot noise. We describe theoretical predictions for the expected magnitude of magnon shot noise, highlighting ambiguities that exist. Further, we show that magnon shot noise detection through the standard inverse spin Hall approach is likely impossible due to geometric factors. Implications for future attempts to measure magnon shot noise are discussed.
format Preprint
id arxiv_https___arxiv_org_abs_2307_11218
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle The challenges of measuring spin Seebeck noise
Luo, Renjie
Zhao, Xuanhan
Legvold, Tanner J.
Chen, Liyang
Liu, Changjiang
Hong, Deshun
Bhattacharya, Anand
Natelson, Douglas
Mesoscale and Nanoscale Physics
Just as electronic shot noise in driven conductors results from the granularity of charge and the statistical variation in the arrival times of charge carriers, there are predictions for fundamental noise in magnon currents due to angular momentum being carried by discrete excitations. The inverse spin Hall effect as a transduction mechanism to convert spin current into charge current raises the prospect of experimental investigations of such magnon shot noise. Spin Seebeck effect measurements have demonstrated the electrical detection of thermally driven magnon currents and have been suggested as an avenue for accessing spin current fluctuations. Using spin Seebeck structures made from yttrium iron garnet on gadolinium gallium garnet, we demonstrate the technical challenges inherent in such noise measurements. While there is a small increase in voltage noise in the inverse spin Hall detector at low temperatures associated with adding a magnetic field, the dependence on field orientation implies that this is not due to magnon shot noise. We describe theoretical predictions for the expected magnitude of magnon shot noise, highlighting ambiguities that exist. Further, we show that magnon shot noise detection through the standard inverse spin Hall approach is likely impossible due to geometric factors. Implications for future attempts to measure magnon shot noise are discussed.
title The challenges of measuring spin Seebeck noise
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2307.11218