Magnetoelastic Coupling in Iron-based Superconductors

Daniel Parshall (University of Colorado)

The cause of high-temperature superconductivity in the iron-based systems remains a mystery. While density function theory (DFT) calculations indicate that conventional electron-phonon coupling is not responsible, there is nevertheless a strong relationship between the lattice and superconductivity (e.g., reports of an isotope effect due to Fe, strong dependence of superconducting temperature upon the Fe-As-Fe bond angle, or alternatively pnictide height).

In addition, there is strong coupling between the lattice and magnetism, which manifests several ways. I will discuss results on FeTe which indicate that the structural transition is strongly affected by the competition between commensurate and incommensurate magnetism. This magnetoelastic coupling has additional effects on the phonon spectrum. I will present data from SrFe2As2 showing the effects of magnetism, particularly on the in-plane phonon modes.

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