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.

铁基超导体（iron-based superconductors, Fe-SC）是凝聚态物理领域最具活力与挑战性的研究课题之一。近期，本团队部分成员（F. Bernardini等人）在新型硅化物LaFeSiH中报道了临界转变温度Tc=11 K的超导电性。LaFeSiH是首款不含有毒元素的铁基超导体。密度泛函理论（Density Functional Theory, DFT）计算结果表明，LaFeSiH的超导特性属于非常规超导电性范畴，无法通过传统BCS理论中的电子-声子耦合机制加以解释。鉴于厘清LaFeSiH与其他已知铁基超导体在配对机制上的异同具有极高的研究价值，我们拟利用MARI/MERLIN谱仪对LaFeSiH超导态下的自旋共振能（spin resonance energy, ER）展开研究。将自旋共振能与超导能隙能量进行对比，可为揭示能隙的符号变化提供关键信息。