Pressure-Induced Superconductivity in Iron-Based Spin-Ladder Compound BaFe(2+δ)(S(1−x)Se(x))(3)

The iron-based superconductors had a significant impact on condensed matter physics. They have a common structural motif of a two-dimensional square iron lattice and exhibit fruitful physical properties as a strongly correlated electron system. During the extensive investigations, quasi-one-dimensional iron-based spin-ladder compounds attracted much attention as a platform for studying the interplay between magnetic and orbital ordering. In these compounds, BaFe(2)S(3) and BaFe(2)Se(3) were found to exhibit superconductivity under high pressure, having a different crystal and magnetic structure at low temperature. We report a brief review of the iron-based spin-ladder compound and recent studies for BaFe(2+δ)(S(1−x)Se(x))(3). BaFe(2)(S(0.75) Se(0.25))(3) is in the vicinity of the boundary of two different magnetic phases and it is intriguing to perform high pressure experiments for studying superconductivity, since effects of large magnetic fluctuations on superconductivity are expected. The effect of iron stoichiometry on the interplay between magnetism and superconductivity is also studied by changing the iron concentration in BaFe(2+δ)Se(3).