engleski

Hall effect study of FeSe1-xSx : search for signatures of quantum criticality

FeSe1-xSx is unique among unconventional superconductors (SC) because its SC state emerges from an electronic nematic state which exists in isolation and therefore provides an opportunity to study the influence of nematic fluctuations on high-temperature SC. On substitution of Se with S, the nematic transition is effectively suppressed and seems to vanish for x=0.16 while the SC temperature Tc = 8-10 K stays almost unaffected. Classic signatures of quantum criticality were found in dc transport: a peculiar T-linear resistivity at the quantum critical point (QCP) x=0.16, a crossover from the T-linear to the Fermi liquid T2 resistivity at low T away from the QCP, and an enhancement in the coefficient of the T2 resistivity on approaching the QCP. Recently, it was found that the magnetoresistance of FeSe1-xSx consists of two components, an orbital component that varies quadratically with magnetic field and a second component that exhibits the unusual quadrature scaling seen in other metals at or close to a QCP. In this presentation, we report our search for signatures of quantum criticality in the corresponding Hall response of FeSe1-xSx carried out on a series of single crystalline samples spanning the QCP in magnetic fields up to 33 T. A conventional, multi-band model does not appear to 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.

unconventional superconductivity, electronic nematicity, quantum criticality, dc resistivity, magnetoresistance, Hall effect, quadrature scaling

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