Non-local Transport in the Topological Surface States of Thin HfTe₅ Devices

Transition metal pentatellurides (ZrTe₅, HfTe₅) are layered van der Waals materials with a C_mcm orthorhombic structure and strain-tuned ground states near the boundary between weak and strong topological insulator phases. They exhibit non-trivial band topology and phenomena such as the chiral magnetic, anomalous Hall, and 3D quantum Hall effects. [1] Topological surface states, characterized by spin–momentum locking, provide a platform for exploring topological superconductivity, spintronic applications, and quantum information technologies. Here, I present comprehensive studies of nonlocal transport in cleaved samples ranging from micron-scale to less than 50 nm. I will discuss the observed decrease in bulk carrier density, the monotonic change in resistance with temperature, and their implications for bulk and surface-state conduction in HfTe₅.

[1] Liu, J., Zhou, Y., Yepez Rodriguez, S. et al. Controllable strain-driven topological phase transition and dominant surface-state transport in HfTe₅. Nat Commun 15, 332 (2024).