Sebastian Goennenwein
In conventional antiferromagnets, transverse transport phenomena such as the anomalous (spontaneous) Hall or Nernst effects must vanish owing to symmetry reasons. In contrast, altermagnetic materials – a new class of magnetic materials with zero net magnetic moment, however featuring broken time reversal symmetry and momentum-dependent spin splitting – do allow for finite spontaneous transverse transport response [1].
In the presentation, I will discuss our recent experiments with Mn5Si3 thin films [2]. Owing to a dominant antiferromagnetic exchange interaction, the net magnetic moment of the films is vanishingly small. Nevertheless, we observe a large and strongly hysteretic anomalous Hall effect in our samples, which characteristically depends on film crystallinity. In addition, the samples also show a non-trivial Nernst response. All these experimental findings can be straightforwardly rationalised in terms of the altermagnetic properties of Mn5Si3 proposed by theory [1].
[1] L. Smejkal, J. Sinova, and T. Jungwirth, Phys. Rev. X 12, 040501 (2022) [2] H. Reichlova et al., arXiv:2012.15651