We have studied the effect of RE substitution on the structure and the local atomic disorder in REO0.5F0.5BiS2 (RE = rare-earth) to understand their correlation with the bulk superconductivity in these materials. The mean RE size, affecting the chemical pressure, has been varied in two series namely Ce1-xNdxO0.5F0.5BiS2 and Nd1-ySmyO0.5F0.5BiS2. The lattice parameters evolve anomalously, showing an anisotropic shrinkage (elongation) of the c-axis (a-axis) to an isotropic expansion of the lattice with increasing mean RE size. The Bi L-3-edge extended X-ray absorption fine structure (EXAFS) measurements are performed to investigate local displacements in the BiS2 lattice, revealing a large disorder and a sharp boundary between the Ce-containing and Sm-containing series with a distinct local structure. The results suggest that the bulk superconductivity in REO0.5F0.5BiS2 is correlated with anomalous atomic displacements in the Bi-S1 network, likely to be a combined effect of active Bi 6s electronic states and a possible Jahn-Teller-like instability of the Bi 6p(x)/6p(y) electrons.
The effect of RE substitution in layered REO0.5F0.5BiS2: Chemical pressure, local disorder and superconductivity / Mizuguchi, Y.; Paris, Eugenio; Sugimoto, T.; Iadecola, A.; Kajitani, J.; Miura, O.; Mizokawa, T.; Saini, Naurang Lal. - In: PHYSICAL CHEMISTRY CHEMICAL PHYSICS. - ISSN 1463-9076. - 17:34(2015), pp. 22090-22096. [10.1039/c5cp03750f]
The effect of RE substitution in layered REO0.5F0.5BiS2: Chemical pressure, local disorder and superconductivity
PARIS, EUGENIO;SAINI, Naurang Lal
2015
Abstract
We have studied the effect of RE substitution on the structure and the local atomic disorder in REO0.5F0.5BiS2 (RE = rare-earth) to understand their correlation with the bulk superconductivity in these materials. The mean RE size, affecting the chemical pressure, has been varied in two series namely Ce1-xNdxO0.5F0.5BiS2 and Nd1-ySmyO0.5F0.5BiS2. The lattice parameters evolve anomalously, showing an anisotropic shrinkage (elongation) of the c-axis (a-axis) to an isotropic expansion of the lattice with increasing mean RE size. The Bi L-3-edge extended X-ray absorption fine structure (EXAFS) measurements are performed to investigate local displacements in the BiS2 lattice, revealing a large disorder and a sharp boundary between the Ce-containing and Sm-containing series with a distinct local structure. The results suggest that the bulk superconductivity in REO0.5F0.5BiS2 is correlated with anomalous atomic displacements in the Bi-S1 network, likely to be a combined effect of active Bi 6s electronic states and a possible Jahn-Teller-like instability of the Bi 6p(x)/6p(y) electrons.File | Dimensione | Formato | |
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