# Time reversal symmetry-protected transport at correlated oxide interfaces

## TL;DR

Researchers found a new type of quantum transport at oxide interfaces, protected by time-reversal symmetry and linked to unique domain walls.

## Contribution

Discovery of TRS-protected transport along quasi-1D domain walls in oxide interfaces with anomalous quantum oscillations.

## Key findings

- A TRS-protected subband was observed at ultra-clean LaAlO3/SrTiO3 interfaces.
- Quantum oscillations showed light electron mass, aperiodicity, and strong magnetic susceptibility.
- Transport occurs along domain walls with Dirac band topology and giant Rashba coupling.

## Abstract

Time-reversal symmetry (TRS) protection is core to topological physics, yet its role in correlated oxides—typically non-topological—remains underexplored. This limit hampers the potential in engineering exotic quantum states by fusing TRS protection and rich emergent phenomena in the oxide platform. Here, we report evidence of a TRS-protected subband at oxygen vacancy-free LaAlO3/SrTiO3 interfaces. This subband causes a low-field quantum oscillation with anomalous characteristics: exceptionally light electron mass, aperiodicity, and susceptibility to magnetic fields. All findings align with a Rashba model in which TRS-protected transport occurs along quasi-1D ferroelastic domain walls, which possess a Dirac band topology and a giant Rashba spin-orbit coupling, two orders stronger than the 2D interface. Our results deepen the understanding of SrTiO3-based electron systems, unveiling an appealing new platform for quantum engineering.

A low-field anomalous quantum oscillation is discovered at ultra-clean LaAlO3/SrTiO3 interfaces, which is attributed to the time-reversal symmetry-protected transport along quasi-1D ferroelastic domain walls.