Transport evidence of Chern gapped Dirac fermions in the kagome magnet TbMn6Sn6

The kagome magnet TbMn6Sn6 is a new member of correlated topological metals, featuring Chern gapped Dirac fermions from the spinless Haldane model. Here we report combined electric and thermal transport study of TbMn6Sn6. Quantum oscillations are observed both in magnetoresistance and magneto-thermopower. The derived Fermi length, the cyclotron mass and their angle-dependence confirm the picture of 2D Dirac dispersion in this hard magnet. Besides, we observe complex Fermi surfaces arising from interlayer interactions, which probably consist of 2D networks and 3D sheets. We also found a phase reversal in the thermal conductivity oscillations, which may be related to competition between electronic contribution and electron-phonon interaction in thermal conductivity. Our observations provide crucial information for theoretical modelling this quantum material.