Neutron Spin resonance in the Fe-based silicide superconductor LaFeSiH

The iron-based superconductors (Fe-SC) are one of the most active and challenging topics in condensed matter physics. Very recently some of us (F. Bernardini et al.) have reported superconductivity in novel silicide LaFeSiH at Tc = 11 K. LaFeSiH is the first Fe-SC without toxic element. DFT calculations have revealed that the superconducting properties of LaFeSiH are unconventional in the sense that they cannot be explained by the electron-phonon mechanism in conventional BCS theory. Given the utmost importance of understanding the similarities and differences in the pairing mechanism with other known Fe-based SC, we want to investigate the spin resonance energy (ER) in the superconducting state of LaFeSiH using the MARI/MERLIN spectrometer. By comparing the value of resonance energy with the superconducting gap energy will provide important information on the sign change of the gap.