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Influence of nematic quantum critical point on the Hall effect in FeSe1-xSx

The existence of a quantum critical point (QCP) beneath the superconducting dome and its role in the superconducting mechanism have been long- standing issues that remain unresolved in many classes of unconventional superconductors, notably cuprates, heavy fermions, and, most recently, iron pnictides. FeSe1-xSx belongs to the class of iron-based superconductors where the superconductivity emerges from an electronic nematic state which exists in isolation and therefore provides a unique opportunity to study the influence of nematic fluctuations on high- temperature superconductivity. Substitution of Se with S effectively suppresses the nematic transition which is believed to terminate inside the superconducting dome at x = 0.16. DC transport measurements revealed classic signatures of quantum criticality: a strictly linear temperature (T) dependence of resistivity at the QCP x = 0.16, a crossover from the T- linear to the Fermi liquid T 2 resistivity at low temperatures away from the QCP, and an enhancement in the coefficient of the T 2 resistivity on approaching the QCP. Recently, it was shown that the magnetoresistance of FeSe1- xSx can be decomposed into two distinct components: one that varies quadratically with magnetic field and one that follows precisely the unusual quadrature scaling seen in other metals at or close to a QCP. Here we report our search for signatures of quantum criticality in the corresponding Hall response of FeSe1-xSx. Measurements were carried out on a series of single crystalline samples spanning the QCP in magnetic fields up to 33 T. It appears that a conventional, multi-band model does not capture the longitudinal and Hall resistivities self- consistently, suggesting that indeed there is a corresponding component in the Hall resistivity associated with the quantum critical sector.

nematicity, quantum criticality, Hall effect, superconductivity, high fields

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