Scanning Tunneling Microscopy Study of 1D Modes Trapped by Topological Defects in Pb_1−xSn_xSe

Defects such as step edges and dislocations in topological crystalline insulators (TCIs), can host topological protected states which connect Dirac points in momentum space. Features like high spin polarization, robustness against magnetic perturbation and temperature, make these topological states suitable for spintronics applications. Here we present a scanning tunneling microscopy (STM) study of 1D modes trapped by two different edge defects in Pb_1−xSn_xSe: screw dislocations and step edges. The differential conductance (dI/dV) maps show an enhancement of the density of states at the Dirac point energy. Previous data on step edges showed no dependence on magnetic field. Interestingly, in our work we find that while some step edges show peaks that are independent of magnetic field, other edges show magnetic field dependence. We will discuss the implications of our findings on the topologically protected 1D states expected in these materials.