Thermal transport, magnetism, and quantum oscillations in Weyl semimetal BaMnSb2

Topological semimetals host unique electronic phases with either Dirac or Weyl characteristic. One way to obtain the Weyl phase is to break the time-reversal symmetry by establishing magnetic ordering. We have investigated the electrical and magnetic properties of a magnetic Weyl semimetal candidate BaMnSb2 under the application of magnetic field (H) up to 35 T. We find that BaMnSb2 undergoes three magnetic phase transitions with a ferromagnetic transition at T-C similar to 690 K and two antiferromagnetic transitions at T-N1 similar to 286 K and T-N2 similar to 450 K. At low temperatures, both the Shubnikov-de Haas and de Haas-van Alphen oscillations are observed by applying H along the c axis of BaMnSb2. Data analysis indicates that the oscillations result from a single band, and the system can reach the first Landau level at high H. Evidence for Zeeman splitting is also observed at low Landau levels, which yields the Lande factor g similar to 8.9 - 10.4. In addition, thermal property measurements reveal very low phonon thermal conductivity and moderate thermopower. The coupling between charge, spin and lattice is discussed.