Central OC Times

Scientists at the University of California, Irvine have made significant strides in understanding superconductivity in an iron-based material. Their research, recently published in Nature, reveals the atomic-scale mechanics that enhance this phenomenon.

Utilizing advanced spectroscopy tools at the UC Irvine Materials Research Institute, the team was able to image atom vibrations and identify new phonons at the interface of an iron selenide (FeSe) ultrathin film on a strontium titanate (STO) substrate. Lead author Xiaoqing Pan explained, “Primarily emerging from the out-of-plane vibrations of oxygen atoms at the interface and in apical oxygens in STO, these phonons couple with electrons due to the spatial overlap of electron and phonon wave functions at the interface.” This interaction provides a mechanism for enhancing superconductivity transition temperature in ultrathin FeSe.

The researchers discovered that FeSe transitions to superconductivity at 65 Kelvin or approximately minus 340 degrees Fahrenheit, marking it as a high-temperature superconductor within its category. They observed that greater uniformity at the FeSe/STO interface leads to higher temperatures for superconductivity onset.

Pan highlighted their methodology: “Our vibrational spectroscopy approach enabled us to achieve highly detailed imaging of the vibrations at the superconducting material’s interface with its substrate.” The findings demonstrate how interlayer spacing affects electron-phonon coupling strength and thus superconductivity.

Co-author Ruqian Wu emphasized collaboration's role: “The ultrahigh spatial and energy resolutions of state-of-the-art instruments at IRMI provide exceptional experimental data for theoretical analysis.” This partnership between theoretical simulations and experimental observations enhances understanding of superconductivity at heterogeneous interfaces.

Pan noted that these results are crucial for advancing scalable fabrication and utilization of superconductors across various applications such as quantum computing, magnetic levitation transportation, and medical devices.

The study involved collaborations with researchers from Uppsala University in Sweden, Princeton University, Beijing National Laboratory for Condensed Matter Physics, and China's Institute of Physics. Support came from the U.S. Department of Energy’s Office of Basic Energy Sciences.

UC Irvine's Brilliant Future campaign aims to raise awareness and support by engaging alumni and securing philanthropic investments. More information about UC Irvine can be found on their website.