Electrical Detection of Single-Domain Néel Vector Reorientation across the Spin–Flop Transition in Cr₂O₃ Crystals

Electrical transport measurements in heterostructures of antiferromagnetic Cr₂O₃ bulk crystals and a thin Pt layer exhibit sharp responses as the Néel vector of Cr₂O₃ undergoes the spin-flop transition. This abrupt change can arise from several distinct mechanisms including magnetostriction, proximity-induced anomalous Hall, spin Hall anomalous Hall, and spin Hall planar Hall effects. While large Pt devices sensing multiple up/down domains can produce indistinguishable Hall signal jumps due to different initial Néel vector orientations, smaller Pt devices that sense single domains isolate the proximity-induced Hall signals. This allows direct electrical detection of Néel vector reorientation across the spin-flop transition in single-domain regions. Furthermore, the single-domain state can be prepared by magnetic field cooling or magnetoelectric cooling. We demonstrate a method to control and characterize the three-dimensional orientation of single-domain Néel vectors by exploiting Hall measurements and cooling techniques, crucial for future antiferromagnetic spintronic applications.