The tunability of topological surface states and the controllable opening of the Dirac gap are two keys for the study of topological crystalline insulators (TCIs). By constructing PbTe/SnTe heterostructures, we discover giant linear magnetoresistance (GLMR) $(2150\%$ under a magnetic field of 14 T at 2 K) and strong metallic behavior that are likely induced by Dirac fermions with a high carrier mobility. By decreasing the hole density in SnTe, a much weaker metallic behavior and two-dimensional weak antilocalization are exhibited in PbTe/SnTe heterostructures. This striking transport difference is attributed to the cubic-rhombohedral structural phase transition in SnTe and broken mirror symmetry effect. The revelation of lattice structural distortion and mirror symmetry breaking in a PbTe/SnTe heterostructure's transport properties is very significant to the fundamental research in topological matter, magnetoelectronics, and spintronics.

• Received 7 May 2018

DOI:https://doi.org/10.1103/PhysRevB.98.161301