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

Abstract

Recent breakthroughs in the electrical detection and manipulation of antiferromagnets have opened a new avenue in the research of non-volatile spintronic devices1,2,3,4,5,6,7,8,9,10. 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 chips10. 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 diffraction11 and X-ray magnetic dichroism measurements12,13,14,15,16.

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Figure 1: Experimental observation of uniaxial magnetic anisotropy in a 10 nm film of CuMnAs.
Figure 2: Determination of spin axis direction by the MO experiment.
Figure 3: Verification of spin axis direction by XMLD.
Figure 4: Determination of Néel temperature.

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Acknowledgements

This work was supported by the Grant Agency of the Czech Republic (grant no. 14-37427G), by the EU ERC (advanced grant no. 268066), by the Ministry of Education of the Czech Republic (grant no. LM2015087), by the University of Nottingham EPSRC Impact Acceleration Account and by the Grant Agency of Charles University in Prague (grants nos. 1910214 and SVV–2015–260216). The authors acknowledge the Diamond Light Source for the provision of beamtime (proposal no. SI-9993).

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R.P.C., V.H. and V.N. prepared the samples. P.N., P.W., B.L.G., P.M. and T.J. planned the experiments. V.S. and F.T. performed the MO experiments. V.H. performed the electrical measurements. P.W., K.W.E., F.M. and S.S.D. performed the XMLD experiment. J.K. and J.Z. performed the XMLD calculations. P.N., V.S. and T.J. wrote the manuscript with contributions from all authors.

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Correspondence to P. Němec.

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Saidl, V., Němec, P., Wadley, P. et al. Optical determination of the Néel vector in a CuMnAs thin-film antiferromagnet. Nature Photon 11, 91–96 (2017). https://doi.org/10.1038/nphoton.2016.255

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