Playing with the dimensionality in iron-based superconductors: quasi-one dimensional iron chalcogenide BaFe2S3

AMIGÓ, M. LOURDES

Conferencia; KATHMANDU HUMBOLDT-KOLLEG 2022 (KHK - 2022) Interdisciplinary Collaboration for Strengthening Science and Culture; 2022

Inrecent years, the study of iron-based superconductors have been oneof the central topics in condensed matter physics. This interest hasbeen triggered by the possibility of improving the understanding of complex phenomena such as high-temperature superconductivity instrongly correlated materials. Among the different aspects that mayplay an important role lies the layered crystal structure, acharacteristic shared by most of the iron- and copper-basedsuperconductors. A natural question of interest is how the superconductivity evolves as the crystal dimensionality is further reduced.This question can be experimentally addressed sinceiron-chalcogen-based structures are extremely flexible and allow theexploration of dimensionality effects on the physical properties.Indeed, in several compounds, the iron atoms form low-dimensionalstructures such as chains (e.g. BaFe2S4)or ladders (BaFe2S3).In particular, BaFe2S3and BaFe2Se3are antiferromagnetic semiconductorsand have been reported to become superconductors under hydrostaticpressure.However,several reports present a sampledependencyonthemagnetic ordering temperature TN,as well as inthepresence of superconductivity inBaFe2S3.It has been argued that the Fe content may play a decisive role, withthe use of 5 mol% excess Fe being reportedly required during thesynthesis to optimize the magnetic ordering temperature and thesuperconducting properties. Inthis talk I will present that ratherthan with the value of excessFe,theantiferromagnetic transitionseemsto correlate with the broadening in the logarithmic derivative of theresistivity around TNthat could be an indicator of the level of disorder in the samples.Moreover,I willintroduce a novel approach for the growth of high quality singlecrystals of BaFe2S3basedon a laser-assisted floating zone method that yields largehomogeneoussamples free of ferromagnetic impurities.