Maximizing T <sub>c</sub> by tuning nematicity and magnetism in FeSe<sub>1-x</sub> S <sub>x</sub> superconductors.
basic_science · Level V
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- Record sourced from PubMed, PMID 29070845.
- Also identified by DOI 10.1038/s41467-017-01277-x and PMC identifier 5656606.
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Abstract
A fundamental issue concerning iron-based superconductivity is the roles of electronic nematicity and magnetism in realising high transition temperature (T <sub>c</sub>). To address this issue, FeSe is a key material, as it exhibits a unique pressure phase diagram involving non-magnetic nematic and pressure-induced antiferromagnetic ordered phases. However, as these two phases in FeSe have considerable overlap, how each order affects superconductivity remains perplexing. Here we construct the three-dimensional electronic phase diagram, temperature (T) against pressure (P) and isovalent S-substitution (x), for FeSe<sub>1-x</sub> S <sub>x</sub> . By simultaneously tuning chemical and physical pressures, against which the chalcogen height shows a contrasting variation, we achieve a complete separation of nematic and antiferromagnetic phases. In between, an extended non-magnetic tetragonal phase emerges, where T <sub>c</sub> shows a striking enhancement. The completed phase diagram uncovers that high-T <sub>c</sub> superconductivity lies near both ends of the dome-shaped antiferromagnetic phase, whereas T <sub>c</sub> remains low near the nematic critical point.