Interplay of magnetism and superconductivity in BaFe2Se3

Figure caption: The phase diagram of BaFe2Se3 under pressure. The deduced integrated absolute difference (IAD) which is proportional to the Fe local moment is shown as the red squares (300 K), blue circles (100 K), and green triangles (17K).
Figure caption: The phase diagram of BaFe2Se3 under pressure. The deduced integrated absolute difference (IAD) which is proportional to the Fe local moment is shown as the red squares (300 K), blue circles (100 K), and green triangles (17K).

The interplay of magnetism and superconductivity in iron-based superconductors remains a subject of extensive studies. Recently, pressure induced superconductivity was observed in Fe-ladder compound BaFe2S3, a quasi-one-dimensional prototype of iron-based superconductors. However, it is unclear whether the mechanism of superconductivity in BaFe2S3 is similar to two-dimensional iron-based superconductors. By combining the measurements of electric resistance, magnetic susceptibility, and Fe-Kb x-ray emission spectroscopy at HPCAT,  a research team observed superconductivity in a compressed BaFe2Se3 sample, with the results implying a new family of iron-based superconductors for such one dimensional Fe-ladder compounds . The local magnetic moment continuously decreases with increasing pressure, and the superconductivity appears only when the local magnetic moment value is comparable to the one in the iron-pnictide superconductors. The new results support the intimate interplay among the magnetism, the crystalline lattice, and the electronic structure in this material. Despite the crystal structures completely different from the known iron-based superconducting materials, the magnetism in this Fe-ladder material may play a critical role in the superconductivity. Thus, magnetic properties become important in elucidating the mechanism of superconductivity, which provides a link to the other members of iron-based superconducting materials.  Details in Ying et al., Phys. Rev. B, 95, 241109(R) 2017.