Optical determination of the Néel vector in a CuMnAs thin-film antiferromagnet

Due to their nature antiferromagnets are difficult to probe with conventional magnetometers. The Néel vector of a practically important antiferromagnet, CuMnAs, has now been determined by a femtosecond pump–probe magneto-optical experiment. Recent breakthroughs in the electrical detection and manipulation of antiferromagnets have opened a new avenue in the research of non-volatile spintronic devices 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 . Antiparallel spin sublattices in antiferromagnets, producing zero dipolar fields, lead to insensitivity to magnetic field perturbations, multi-level stability, ultrafast spin dynamics and other favourable characteristics, and may find utility in fields ranging from magnetic memories to optical signal processing. However, the absence of a net magnetic moment and ultrashort magnetization dynamics timescales make antiferromagnets notoriously difficult to study using common magnetometers or magnetic resonance techniques. Here, we demonstrate the experimental determination of the Néel vector in a thin film of antiferromagnetic CuMnAs (refs 9 , 10 ), a prominent material used in the first realization of antiferromagnetic memory chips 10 . We use a table-top femtosecond pump–probe magneto-optical experiment that is considerably more accessible than the traditionally employed large-scale-facility techniques such as neutron diffraction 11 and X-ray magnetic dichroism measurements 12 , 13 , 14 , 15 , 16 .