Breakthrough in Iron-Based Superconductivity Revealed

Researchers at the University of California, Irvine have discovered important atomic-scale mechanisms that improve superconductivity in an iron-based material. Their findings, published in Nature, provide new insights into how these materials function at the atomic level.

Using advanced spectroscopy tools at the UC Irvine Materials Research Institute (IMRI), the team studied iron selenide (FeSe) ultrathin films placed on a strontium titanate (STO) substrate. This enabled them to observe new phonons—quasiparticles that carry thermal energy—at the interface between the two materials.

The phonons observed mainly arise from the vibrations of oxygen atoms at the interface, which interact with electrons due to the overlap of their wave functions. This interaction, known as electron-phonon coupling, plays a crucial role in enhancing the transition temperature for superconductivity in FeSe.

The study revealed that FeSe becomes superconductive at 65 Kelvin (-340°F), the highest transition temperature observed among similar materials. The researchers found that a more uniform interface between FeSe and STO leads to higher superconducting temperatures.

The research also highlighted how the spacing between the layers of FeSe and STO influences the strength of the electron-phonon coupling and, consequently, the superconducting properties. The team’s vibrational spectroscopy approach allowed them to capture detailed images of these atomic vibrations at the material's interface.

By combining experimental data with theoretical simulations, the researchers were able to pinpoint the individual atomic contributions that enhance superconductivity. This work marks a significant step toward making superconductors more applicable for technologies such as quantum computing, magnetic levitation transportation, and advanced medical devices.