with Weyl semimetallic and trivial semimetallic phases

Quantum materials with non-trivial electronic topologies are one of the most active fields of current condensed matter research. Among them, Weyl semimetal (WSM) behavior can be realized quite generally in a semimetallic crystal with large spin-orbit coupling by breaking either time-reversal or space inversion symmetry. Interestingly, those known WSMs through the space inversion breaking mechanism often crystallize in polar structures, and thus they are polar WSMs. The question that naturally arises is the possible existence of polar domains and domain walls (DWs), which is particularly important because the Weyl points and the surface Fermi-arcs can depend on the domain reorientation and accompany with intriguing properties. Here, we focus on the type-II WSM MoTe₂, which has recently drawn an immense attention due to its phase tunability and unique physical properties. Utilizing in-situ cryogenic transmission electron microscopy, we unveil intriguing polar domain structures in MoTe₂. We also discover unexpected domain kinetics under electron beams. Using spatially resolved tunneling spectroscopy, we observe distinct electronic responses of those domains and DWs. These findings are a key step toward engineering the Weyl-node-pair-related physical properties in such polar WSMs.