Detectable signatures of topology of the band structures in 3d semimetals

We will elucidate the nature of the linear-response tensors in 
planar-Hall and planar-thermal-Hall set-ups, where we subject a 3d 
semimetal (harbouring nodal points of topological nature) to the 
combined influence of an electric field (and/or temperature gradient) 
and a weak (i.e., non-quantising) magnetic field. We will explain why it 
is essential to include the effects of the intrinsic orbital magnetic 
moment of the wavepackets in conjunction with the Berry curvature, in 
order to obtain a holistic picture of the effects of the topology of the 
Brillouin zone in the linear-response tensors. Going beyond the 
well-studied example of Weyl semimetals, we will discuss the cases of 
their multifold cousins, harbouring higher Chern numbers. We will 
highlight how we can compute the exact solutions from the Boltzmann 
equations, which gets rid of the often-inaccurate results of the naive 
relaxation-time approximation. Finally, we will outline how to derive 
surface states, in the form of Fermi arcs, characterising generic nodal 
points.