Electronic phase diagram of iron chalcogenide superconductors FeSe1-xSx and FeSe1-yTey

TL;DR

This study maps the electronic phase diagram of FeSe-based superconductors, revealing that the tetragonal phase hosts superconductivity and that the Hall coefficient dip correlates with Tc, providing insights into the underlying mechanisms.

Contribution

It presents a comprehensive phase diagram of FeSe1-xSx and FeSe1-yTey, showing the tetragonal phase's role in superconductivity and the correlation between Hall coefficient features and Tc.

Findings

No orthorhombic transition in FeSe1-yTey samples

Hall coefficient dip correlates with superconducting Tc

Tetragonal phase is fundamental for superconductivity

Abstract

Here we establish a combined electronic phase diagram of isoelectronic FeSe1-xSx (0.19 > x > 0.0) and FeSe1-yTey (0.04 < y < 1.0) single crystals. The FeSe1-yTey crystals with y = 0.04 - 0.30 are grown by a hydrothermal ion-deintercalation (HID) method. Based on combined experiments of the specific heat, electrical transport, and angle-resolved photoemission spectroscopy, no signature of the tetragonal-symmetry-broken transition to orthorhombic (nematic) phase is observed in the HID FeSe1-yTey samples, as compared with the FeSe1-xSx samples showing this transition at Ts. A ubiquitous dip-like temperature dependence of the Hall coefficient is observed around a characteristic temperature T* in the tetragonal regimes, which is well above the superconducting transition. More importantly, we find that the superconducting transition temperature Tc is positively correlated with the Hall-dip temperature T* across the FeSe1-xSx and FeSe1-yTey systems, suggesting that the tetragonal background is a fundamental host for the superconductivity.