The strange metal Hall effect connects quantum criticality and superconductivity in an iron-based superconductor

TL;DR

This study reveals a direct link between quantum criticality and superconductivity in an iron-based superconductor through anomalous Hall effect measurements, suggesting a universal connection in strange metals.

Contribution

It demonstrates that the strange metal Hall component originates from a quantum critical point and correlates with the superconducting critical temperature, providing a new understanding of their relationship.

Findings

Anomalous Hall contribution arises from strange metal correlations.

The Hall component decays proportionally to the superconducting critical temperature.

The behavior is tracked across the doping-temperature phase diagram.

Abstract

Many unconventional superconductors exhibit a common set of anomalous charge transport properties that characterize them as `strange metals', which provides hope that there is single theory that describes them. However, model-independent connections between the strange metal and superconductivity have remained elusive. In this letter, we show that the Hall effect of the unconventional superconductor BaFe$_2$(As$_{1-x}$P$_x$)$_2$ contains an anomalous contribution arising from the correlations within the strange metal. This term has a distinctive dependence on magnetic field, which allows us to track its behavior across the doping-temperature phase diagram, even under the superconducting dome. These measurements demonstrate that the strange metal Hall component emanates from a quantum critical point and, in the zero temperature limit, decays in proportion to the superconducting critical temperature. This creates a clear and novel connection between quantum criticality and superconductivity, and suggests that similar connections exist in other strange metal superconductors.