Antiferromagnetic magnetostriction effect in uniaxial antiferromagnet revealed by magnetoresistance probe

Antiferromagnetic materials are expected to play an important role in future spintronic applications thanks to their unique properties, such as robustness against perturbation and terahertz-frequency spin dynamics. However, detection, along with efficient manipulation, of antiferromagnetic order parameter remain to be challenging. In analogy to the ferromagnetic case, spin-Hall magnetoresistance in antiferromagnets has been proposed to detect antiferromagnetic order. Here, we have carried out a systematic study of the magnetoresistance in uniaxial antiferromagnet Cr₂O₃/normal metal heterostructures. By sweeping the external magnetic field, we observed a jump in the magnetoresistance at the spin-flop transition due to the sudden rotation of the Néel order with respect to the current direction. More surprisingly, the jump persists even when a 5nm Al₂O₃ layer is inserted between Pt and Cr₂O₃, which indicates that, in addition to the expected spin-Hall magnetoresistance, the antiferromagnetic magnetostriction effect is also present at the spin-flop transition of the uniaxial antiferromagnet Cr₂O₃ system. Our findings suggest that magnetoresistance measurement in the adjacent metal layer serves as a convenient probe to detect both magnetostriction coefficients and antiferromagnetic order parameter.