Tunable long-distance spin transport in a crystalline antiferromagnetic iron oxide.

Abstract

Spintronics uses spins, the intrinsic angular momentum of electrons, as an alternative for the electron charge. Its long-term goal is to develop beyond-Moore, low-dissipation technology devices, recently demonstrating long-distance transport of spin signals across ferromagnetic insulators1. Antiferromagnetically ordered materials, the most common class of magnetic materials, have several crucial advantages over ferromagnetic systems2. Antiferromagnets exhibit no net magnetic moment, rendering them stable and impervious to external fields. Additionally, they can be operated at THz frequencies3. Although their properties bode well for spin transport4–7, previous indirect observations indicate that spin transmission through antiferromagnets is limited to only a few nanometers8–10. Here we demonstrate the long-distance propagation of spin-currents through single-crystalline hematite (α-Fe2O3)11, the most common antiferromagnetic iron oxide, exploiting the spin Hall effect for spin injection. We control the spin-current flow by the interfacial spin-bias, tuning the antiferromagnetic resonance frequency with an external magnetic field12. This simple antiferromagnetic insulator conveys spin information parallel to the Néel order over distances exceeding tens of micrometers. This newly-discovered mechanism transports spin as efficiently as the net magnetic moments in the best-suited complex ferromagnets1. Our results pave the way to ultra-fast, low-power antiferromagnet-insulator-based spin-logic devices6,13 that operate, without magnetic fields, at room temperature.