# Quantized surface transport in topological Dirac semimetal films

## TL;DR

This paper reports the observation of surface quantum oscillations evolving into quantum Hall states in Cd3As2 topological semimetal films, highlighting the role of bulk states and enabling potential Fermi-arc transport engineering.

## Contribution

It demonstrates controlled surface quantum transport and quantum Hall states in Dirac semimetal films, revealing bulk involvement and tunability of topological surface states.

## Key findings

- Surface quantum oscillations observed in Cd3As2 films.
- Quantum Hall states emerge from surface states with bulk involvement.
- Transport properties depend on bulk occupation and film parameters.

## Abstract

Unconventional surface states protected by non-trivial bulk orders are sources of various exotic quantum transport in topological materials. One prominent example is the unique magnetic orbit, so-called Weyl orbit, in topological semimetals where two spatially separated surface Fermi-arcs are interconnected across the bulk. The recent observation of quantum Hall states in Dirac semimetal Cd3As2 bulks have drawn attention to the novel quantization phenomena possibly evolving from the Weyl orbit. Here we report surface quantum oscillation and its evolution into quantum Hall states in Cd3As2 thin film samples, where bulk dimensionality, Fermi energy, and band topology are systematically controlled. We reveal essential involvement of bulk states in the quantized surface transport and the resultant quantum Hall degeneracy depending on the bulk occupation. Our demonstration of surface transport controlled in film samples also paves a way for engineering Fermi-arc-mediated transport in topological semimetals.