Observation of magnetic Weyl fermion excitation in antiferromagnetic kagome Mn₃Pt thin films

Kagome metals have triggered immense interest in the research community due to their interesting spin-lattice structure giving rise to finite Berry curvature, linearly dispersive band crossings, flat bands, and exotic magnetotransport phenomena [1,2]. Here, we report the observation of linearly dispersive Weyl nodes in strongly correlated kagome Mn₃Pt epitaxial films using magnetotransport measurements and density functional theory (DFT) calculations. We observe a large, non-saturating, positive, transverse magnetoresistance (MR) which changes sign in parallel electric and magnetic fields, confirming the chiral anomaly arises in Weyl semimetals [3]. The chiral anomaly induced negative MR is very sensitive to the angle between electric and magnetic fields. Additionally, we provide evidence of planar Hall signal supporting the presence of chiral anomaly. Moreover, we also find a large anomalous Hall conductivity at low-temperature regime. These results pave the possibilities of new Weyl semimetals in thin films for topo-electronic devices.
References:
[1] Kang et al., Nature Materials 19(2): 163-169, 2020.
[2] Baidya et al., Phys. Rev. Lett., 125(2): 026401, 2020.
[3] Kuroda et al., Nature Materials, 16(11):1090–1095, 2017.