Coherent Spin Pumping Originated from Sub-Terahertz Néel Vector Dynamics in Easy Plane
Phys. Rev. Lett. 135, 216704 – Published 19 November, 2025
DOI: https://doi.org/10.1103/zsd7-vbwg
Abstract
We present a thorough study of spin-to-charge current interconversion in bulk and thin films of (0001) heterostructures by means of all-optical polarization-controlled microwave excitation at subterahertz frequencies. Our results demonstrate that coherent spin pumping is generated through excitations of both the quasiferromagnetic and quasiantiferromagnetic (q-AFM) modes of antiferromagnetic resonance, provided that the corresponding selection rules are met for the relative orientation between the microwave magnetic field and the magnetic moment of the hematite. In particular, our results unambiguously show that while a microwave field with pumps a net spin angular momentum from the quasiferromagnetic mode, spin pumping from the q-AFM mode is only enabled when , as expected from the selection rules imposed by the Néel vector dynamics. 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.
