Robust Spin Injection at Antiferromagnet/Ferromagnet Interface*

With ultrafast spin dynamics and robustness against perturbation to magnetic fields, antiferromagnets are promising material candidates for information technologies [1,2]. Spin injection and detection in antiferromagnet-based systems is a prerequisite for the development of next-generation spintronic applications. Here, we demonstrate spin injection from a ferromagnetic metal, Permalloy (Py), into a thin film of an insulating antiferromagnet, Cr2O3. Using temperature gradient as a thermal drive [3], we observe spin pumping by magnons with different sign across the spin-flop transition of Cr2O3. In heterostructures with nonmagnetic metals, Cr2O3/Pt, the spin current rapidly falls with increasing temperature. However, we find the spin current injection from the ferromagnetic metal to rise with increasing temperature and to persist up to the characteristic collapse at the Néel temperature. The results point the way for robust spintronic applications that take advantage of both antiferromagnetic spin dynamics and spin-orbitronic phenomena inherent to ferromagnetic metals.

[1] Baltz et al., Rev. Mod. Phys. 90, 015005 (2018); [2] Etesamirad et al., ACS Appl. Mater. Interfaces 13, 20288 (2021); [3] Arkook et al., arXiv:1909.12445