Electron-lattice coupling in iron-based superconductors

Orateur : Anna BÖHMER (Ames Laboratory, US DOE, Ames, Iowa 50011, USA)

Iron-based materials are distinguished by their complex interplay of structure, magnetism and superconductivity. In typical materials like BaFe2As2, a tetragonal-to-orthorhombic structural distortion (nematicity) is intimately coupled to stripe-type antiferromagnetism, and both order parameters compete with superconductivity. FeSe, in contrast, is discussed as a candidate for non-magnetic nematicity, because its structural transition at 90 K at ambient pressure appears to be unrelated to pressure-induced magnetism. I will present how the evolution of lattice parameters can be used to study and to control the phase interplay in iron-based systems. For example, using synchrotron-based techniques, we study the lattice distortion and the magnetic hyperfine field in FeSe under hydrostatic pressure and demonstrate the strong cooperative coupling between nematic and magnetic order parameters, an important step towards the universal description of the iron-based systems.

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