Observation of Iron Vacancy Order/Disorder and Superconductivity in KFeSe by Neutron Scattering
Jie-Yu Yang1,2*, Chih-Hao Lee1, Maw-Kuen Wu2
1Engineer and system science, National Tsing Hua University, Hsinchu city, Taiwan
2Physics department, Academia Sinica, Taipei city, Taiwan
* Presenter:Jie-Yu Yang, email:sh-159357@hotmail.com
The coexistence or competition of magnetism and superconductivity has been a hot debate since Fe-based superconductors had been discovered in 2008. This discovery of iron chalcogenide superconductors plays an important role in unconventional superconductors, which also may provide distinct view of superconductivity. Our results unambiguously resolve the controversy of the exact parent phase in K2-xFe4+ySe5 system [1]. The magnetic structure in superconducting K2-xFe4+ySe5 samples was examined by neutron diffraction in ANSTO. It is observed that the disappearance of magnetic order at lower temperature than of the Fe-vacancy order. In parent compound K2Fe4Se5, the splitting of magnetic peak and nucleus peak is more obvious than superconducting sample.

[1] C. H. Wang, et al., EPL, 111 (2015) 27004

Keywords: Fe-based superconductor, Fe-vacancy order, superconductivity