Unconventional Quantum Oscillations in Complex Oxide Interfaces

Published September 11, 2025

Schematics of two heterostructures.

When two insulating oxides (e.g., SrTiO₃ and LaAlO₃) are brought together, their interface surprisingly becomes conductive. By studying these oxide interfaces in strong magnetic fields, we discovered unusual behavior in the way electrons move—suggesting a new type of electronic structure. These findings could help advance technologies like quantum computers and data-storage devices.

What is the finding

Researchers discovered unusual electronic behavior at the interfaces of special oxides, where electrons move in surprising patterns that break long-standing theories of quantum physics. According to conventional theory, these oscillations should be periodic in the inverse magnetic field. However, in complex oxide interfaces such as LaAlO₃/SrTiO₃ and LaAlO₃/KTaO₃, the oscillation frequency increases progressively with increasing magnetic field strength, indicating the presence of nontrivial electronic states.

Why is this important?

Despite being made from insulating materials, certain oxide interfaces can conduct electricity and even show superconductivity and magnetism—features useful for future memory and quantum technologies. To understand why and how this works, researchers studied the behavior of electrons at three different oxide interfaces using high magnetic fields. They observed unconventional quantum oscillations, showing that electrons follow unique energy pathways that mix two different types of motion. Our experimental findings and versatile theoretical model also hold promise for comprehending similar observations in other materials with strong spin-orbit coupling, including Dirac and Weyl semimetals.

Who did the research?

K. Rubi¹, D. R. Candido², M. Dumen³, S. Zeng⁴, E. Ammerlaan⁵, F. Bangma⁵, M. Chan¹, M. Goiran⁶, A. Ariando⁴, S. Chakraverty³, W. Escoffier⁶, U. Zeitler⁵, N.Harrison¹

¹National MagLab, Los Alamos National laboratory; ²University of Iowa; ³Institute of Nano Science and Technology, India; ⁴National University of Singapore, Singapore; ⁵HFML-EMFL, Radboud University Netherlands; ⁶LNCMI-EMFL, Toulouse France.

Why did they need the MagLab?

Because electrons do not move very quickly in these oxide interfaces (moderate electron mobility), extremely high magnetic fields—up to 60 T—were essential to resolve the quantum oscillations and see the quantum behavior. Higher magnetic fields are needed to observe a sufficient number of oscillations (typically 8–10) to reliably identify these materials’ unconventional nature.