Efficient magnon transport and magnon torque through the epitaxial antiferromagnetic insulator α-Fe₂O₃

Magnons, as key carriers of spin angular momentum, enable spin transport without charge movement in magnetic insulators, thereby greatly reducing Joule heating in spintronic devices. Magnon-mediated spin torque (i.e., magnon torque) provides an alternative approach for efficient magnetization manipulation. However, magnon transmission through antiferromagnetic insulators still suffers from notable propagation losses, limiting the efficiency of magnon torque. Here, we fabricate high-quality epitaxial α-Fe₂O₃ thin films by magnetron sputtering that exhibit strong antiferromagnetic ordering, and successfully demonstrate highly efficient magnon transport and magnon torque in Pt/α-Fe₂O₃/NiFe devices at room temperature. It is observed that magnons propagate through a 20-nm-thick α-Fe₂O₃ layer with a significantly enhanced transmission efficiency of 75%, about 2.5 times higher than that in previously reported NiO-based magnonic devices. Consequently, a pronounced magnon torque is exerted on the adjacent ferromagnetic layer. Our work demonstrates that α-Fe₂O₃ is a promising antiferromagnetic material for efficient magnon channels, advancing the study of energy-efficient, high-speed magnonic devices.