Role of the local structure in superconductivity of LaO0.5F0.5BiS2−xSex system

• Published in: Journal of physics. Condensed matter Vol. 29; no. 14
• Main Authors: Paris, E, Mizuguchi, Y, Hacisalihoglu, M Y, Hiroi, T, Joseph, B, Aquilanti, G, Miura, O, Mizokawa, T, Saini, N L
• Format: Journal Article
• Language: English
• Published: IOP Publishing 06.03.2017
• Subjects: based superconductors; effect of substitution; local structure and disorder
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/1361-648X/aa5e97

We have studied the local structure of LaO0.5F0.5BiS2−xSex by Bi L1-edge extended x-ray absorption fine structure (EXAFS). We find a significant effect of Se substitution on the local atomic correlations with a gradual elongation of average in-plane Bi-S bondlength. The associated mean square relative displacement, measuring average local distortions in the BiS2 plane, hardly shows any change for small Se substitution, but decreases significantly for x 0.6. The Se substitution appears to suppress the local distortions within the BiS2 plane that may optimize in-plane orbital hybridization and hence the superconductivity. The results suggest that the local structure of the BiS2-layer is one of the key ingredients to control the physical properties of the BiS2-based dichalcogenides.