Interplay of the electronic and lattice degrees of freedom in A_{1-x}Fe_{2-y}Se_{2} superconductors under pressure

Abstract

The local structure and electronic properties of Rb${}_{1-x}$Fe${}_{2-y}$Se${}_2$ are investigated by means of site selective polarized x-ray absorption spectroscopy at the iron and selenium K-edges as a function of pressure. A combination of dispersive geometry and novel nanodiamond anvil pressure-cell has permitted to reveal a step-like decrease in the Fe-Se bond distance at $p\simeq 11$ GPa. The position of the Fe K-edge pre-peak, which is directly related to the position of the chemical potential, remains nearly constant until $\sim 6$ GPa, followed by an increase until $p\simeq 11$ GPa. Here, as in the local structure, a step-like decrease of the chemical potential is seen. Thus, the present results provide compelling evidence that the origin of the reemerging superconductivity in $A_{1-x}$Fe${}_{2-y}$Se${}_2$ in vicinity of a quantum critical transition is caused mainly by the changes in the electronic structure.

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Cited by in corpus (7)

• Temperature dependence of iron local magnetic moment in phase-separated superconducting chalcogenide
• Origin of Pressure-induced Superconducting Phase in K${}_x$Fe${}_{2-y}$Se${}_2$ studied by Synchrotron X-ray Diffraction and Spectroscopy
• Importance of structural distortions in enhancement of transition temperature in FeSe${}_{1-x}$Te${}_x$ superconductors
• Structure, superconductivity, and magnetism in Rb1-xFe1.6Se2-zSz
• $\mathrm{L}{\mathrm{i}}_{\mathrm{x}}({\mathrm{C}}_5{\mathrm{H}}_5\mathrm{N}{)}_{\mathrm{y}}\mathrm{F}{\mathrm{e}}_{2-\mathrm{z}}\mathrm{S}{\mathrm{e}}_2$: a defect resilient expanded-lattice high-temperature superconductor
• Formation of single-phase disordered CsxFe2-ySe2 at high pressure
• Multiband behavior and non-metallic low-temperature state of K${}_{0.50}$Na${}_{0.24}$Fe${}_{1.52}$Se${}_2$