Indium Oxide Films Challenge Superconductivity with Groundbreaking Quantum Phase Transition

A group of physicists at Université Grenoble Alpes, CNRS, in France, in collaboration with a colleague from Karlsruhe Institute of Technology, in Germany, has detected an unusual quantum phase transition in indium oxide films. In their research published in the journal Nature Physics, the team employed microwave spectroscopy to examine the internal properties and dynamics of indium oxide films as they shifted between superconducting and insulating states.

Previous studies have indicated that as a superconductor undergoes a phase transition between superconductivity and insulation, its superfluid stiffness typically occurs in a smooth and continuous manner. Superfluid stiffness is a metric designed to assess how resistant a material is to transitioning from one phase to another. In this latest investigation, the research team uncovered a deviation from this expectation in indium oxide films.

In their analysis, the researchers focused on the characteristics of indium oxide, a substance that transforms into a superconductor when cooled to a certain temperature—and is also known to exhibit multiple disorders at various levels. These disorders impart the material with peculiar attributes.

To delve deeper into these characteristics, the research team initially fabricated indium oxide films to utilize microwave spectroscopy, a method that enables them to observe the superfluid stiffness of a specimen. They discovered that instead of observing the anticipated gradual transition during a phase change prompted by a temperature increase, there was a sudden decline.

Moreover, they noted that during the phase transformation, the critical temperature was not defined by the strength of the Cooper pairs (pairs of electrons that coordinate their movement during transitions)—rather, it was determined by the superfluid stiffness. The researchers were unable to provide a rationale for this phenomenon.

In concluding their investigation, the group remarked that the behavior demonstrated by indium oxide films was not only uncommon but could also pave the way for new explorations involving quantum materials, potentially leading to methods for enhancing their stability.

© 2025 Science X Network