Ginzburg-Landau theory of spin pumping through an antiferromagnetic layer near the Néel temperature
Yuto Furutani, Hayato Fukushima, Yutaka Yamamoto, Masanori Ichioka, Hiroto Adachi
Published: 2025/10/3
Abstract
Spin pumping is a microwave-driven means for injecting spins from a ferromagnet into the adjacent target material. The insertion of a thin antiferromagnetic layer between the ferromagnet and the target material is known to enhance the spin pumping signal. Here, in view of describing dynamic fluctuations of the N\'{e}el order parameter, we develop Ginzburg-Landau theory of the spin pumping in a ferromagnet/antiferromagnet/heavy metal trilayer in the vicinity of the antiferromagnetic N\'{e}el temperature $T_{\rm N}$. When there exists an interfacial exchange interaction between the ferromagnetic spins and the antiferromagnetic N\'{e}el order parameter at the ferromagnet/antiferromagnet interface, we find a strongly frequency-dependent enhancement of the pumped spin current that is peaked at $T_{\rm N}$. The present finding offers an explanation for the enhanced spin pumping with strong frequency dependence observed in a Y$_3$Fe$_5$O$_{12}$/CoO/Pt system.