Observation of zero bias anomaly in noncolinear antiferromagnet/heavy metal heterostructures

Noncolinear antiferromagnets (NC-AFMs) show exotic transport phenomena such as anomalous and topological Hall effect due to their non-vanishing Berry curvature¹. Although many reports have focused on the transport properties of NC-AFMs, we have explored the differential conductance spectroscopy to probe the electronic structure of heterostructured device comprising of NC-AFM, Mn₃Pt, in proximity to heavy metal(Ta). Mn₃Pt/Ta and Ta/Mn₃Pt/Ta heterostructures were grown by co-sputtering on STO (100) substrate. We observe a strong zero bias conductance peak (ZBCP), only in the Mn₃Pt/Ta structure, below 10 K with the peak amplitude increasing with cool down and saturating at 4 K, with a magnitude of 4 times the conductance in the flat regime at high bias. Additionally, we observe sister peaks on both sides of the ZBCP twice in magnitude of conductance in the flat regime. Similar phenomena are reported in Dirac semimetal/superconductor heterostructure² attributed to the superconducting nature of the device. Our study therefore, highlights that such ZBCP may be observed even in non-superconducting devices and may be driven by interface effects in these topologically nontrivial materials.
1. Chen et al., Phys. Rev. Lett., 112, 017205, 2014.
2. Yu et. al., arXiv:1909.08146[cond-mat], 2019.