Coherent Spin Pumping Originated from Sub-Terahertz Néel Vector Dynamics in Easy Plane α-Fe₂O₃/Pt

Journal Article · Wed Jan 01 00:00:00 EST 2025 · Physical Review Letters

DOI:https://doi.org/10.1103/zsd7-vbwg· OSTI ID:2903077

Fritjofson, Gregory ^[1]; Tang, Junyu ^[2]; Regmi, Atul ^[1]; Hanson-Flores, Jacob ^[1]; Michel, Justin ^[3]; Yang, Fengyuan ^[3]; Cheng, Ran ^[2]; Del Barco, Enrique ^[1]

---

1. University of Central Florida
2. University of California, Riverside
3. The Ohio State University

We present a thorough study of spin-to-charge current interconversion in bulk and thin films of (0001) 𝛼-Fe2O3/Pt heterostructures by all-optical polarization-controlled microwave excitation at sub-Terahertz frequencies. Our results demonstrate that coherent spin pumping is generated through excitations of both the q-FM and q-AFM modes of antiferromagnetic resonance, provided that the corresponding selection rules are met. Our findings significantly advance current understanding of spin pumping in easy-plane antiferromagnets not only by claiming a substantial contribution from the Néel-vector dynamics of the q-AFM mode but also by experimentally determining the relative strength of the intra- and cross-sublattice components of the spin-mixing conductance, challenging recent reports where the absence of spin pumping from the q-AFM mode in Hematite was interpreted as a complete cancellation between these two components. We also provide an explanation for the previously reported observations and show how the q-AFM spin pumping actually vanishes for thin films, which we speculate being either due to an increased level of inhomogeneities or to insufficient film thickness for the q-AFM mode to fully realize.

• Research Organization: The Ohio State University; University of California, Riverside; University of Central Florida
• Sponsoring Organization: AFOSR; USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)
• Grant/Contract Number: SC0001304
• OSTI ID: 2903077
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters
• Country of Publication: United States
• Language: English