Strong electron correlations in the normal state of FeSe0.42Te0.58

TL;DR

This study uses angle resolved photoemission to reveal that FeSe0.42Te0.58 exhibits highly renormalized quasiparticle dispersions, indicating strong electron correlations in its normal state, with effective masses significantly exceeding band structure predictions.

Contribution

It provides detailed measurements of effective carrier masses and demonstrates the strong correlation effects in FeSe0.42Te0.58, a novel insight into its electronic properties.

Findings

Effective masses between ~3 - 16 m_e depending on the Fermi surface sheet.

Mass enhancement over band structure of m*/m_band ~ 6 - 20.

Strong correlation effects are comparable to bulk specific heat measurements.

Abstract

We investigate the normal state of the '11' iron-based superconductor FeSe0.42Te0.58 by angle resolved photoemission. Our data reveal a highly renormalized quasiparticle dispersion characteristic of a strongly correlated metal. We find sheet dependent effective carrier masses between ~ 3 - 16 m_e corresponding to a mass enhancement over band structure values of m*/m_band ~ 6 - 20. This is nearly an order of magnitude higher than the renormalization reported previously for iron-arsenide superconductors of the '1111' and '122' families but fully consistent with the bulk specific heat.