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Nonreciprocity in Magnon Mediated Charge-Spin-Orbital Current Interconversion
José Omar Ledesma-Martin1,2, Edgar Galindez-Ruales1, Sachin Krishnia1
1Institute of Physics, Johannes Gutenberg University Mainz, 55099 Mainz, Germany.
Nano Letters
|February 14, 2025
Summary
Introducing the orbital Hall effect (OHE) into nonlocal spintronic devices with yttrium iron garnet (YIG) disrupts angular momentum transport reciprocity. This study reveals a 35% efficiency increase due to OHE-mediated spin vorticity, highlighting orbital effects in spintronics.
Area of Science:
- Spintronics
- Condensed Matter Physics
- Materials Science
Background:
- Angular momentum transport in magnetic systems involves spin and orbital degrees of freedom.
- Nonlocal devices utilize heavy-metal nanowires on magnetic insulators (e.g., YIG) for magnon-mediated angular momentum transport.
- Spin Hall effect (SHE) and inverse SHE (iSHE) are key mechanisms for spin accumulation and detection.
Purpose of the Study:
- To investigate the impact of the orbital Hall effect (OHE) on the reciprocity of angular momentum transport in nonlocal spintronic devices.
- To quantify the efficiency changes introduced by OHE in conjunction with SHE.
- To explore the underlying physical mechanisms, such as spin vorticity, responsible for observed nonreciprocity.
Main Methods:
- Fabrication of nonlocal spintronic devices using heavy-metal (Pt/Ru) layers on yttrium iron garnet (YIG) substrates.
- Utilizing spin Hall effect (SHE) and orbital Hall effect (OHE) for magnon polarization and detection via inverse SHE (iSHE).
- Comparing the efficiency of angular momentum transport in forward and reverse configurations of injector and detector roles.
Main Results:
- The introduction of Ruthenium (Ru), enabling OHE, disrupted the typical reciprocity of spin transport.
- A 35% higher efficiency was observed for magnon transport when polarized by combined SHE and OHE compared to the reverse process.
- Observed nonreciprocity was attributed to nonzero spin vorticity arising from differential electron drift velocities at the Pt/Ru interface.
Conclusions:
- Orbital transport mechanisms, specifically OHE, significantly influence angular momentum transport efficiency in nonlocal spintronic devices.
- The findings demonstrate a potential route to engineer nonreciprocal spin transport by leveraging orbital effects.
- This research opens new avenues for controlling and enhancing spin dynamics in next-generation spintronic technologies.
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