  Nonlinear planar magnetotransport is ubiquitous in topological HgTe
structures, both in tensile (topological insulator) or compressively strained
layers (Weyl semimetal phase). We show that the common reason for the nonlinear
planar magnetotransport is the presence of tilted Dirac cones combined with the
formation of charge puddles. The origin of the tilted Dirac cones is the mix of
the Zeeman term due to the in-plane magnetic field and quadratic contributions
to the dispersion relation. We develop a network model that mimics transport of
tilted Dirac fermions in the landscape of charge puddles. The model captures
the essential features of the experimental data. It should be relevant for
nonlinear planar magnetotransport in a variety of topological and small band
gap materials.
