Search

Mn-based superconductors are very rare and their superconductivity has only been reported in three-dimensional MnP and quasi-one-dimensional KMn6Bi5 and RbMn6Bi5 with [Mn6Bi5]âˆ' columns under high pressures. Here we report the synthesis, magnetism, electrical resistivity, and specific heat capacity of the newly discovered quasi-one-dimensional NaMn6Bi5. Compared with other A Mn6Bi5 (A = K, Rb, and Cs), NaMn6Bi5 has abnormal Bi-Bi bond lengths and two antiferromagnetic-like transitions at 47.3 K and 51.8 K. Anisotropic resistivity and low-temperature non-Fermi liquid behavior are observed. Heat capacity measurement reveals that the Sommerfeld coefficient for NaMn6Bi5 is unusually large. Using first-principles calculations, an unusual enhancement of density of states near the Fermi level is demonstrated for NaMn6Bi5. The features make NaMn6Bi5 a more suitable platform to explore the interplay of magnetism and superconductivity. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract We performed angle-resolved photoemission spectroscopy studies on a series of FeTe 1− x Se x monolayer films grown on SrTiO 3. The superconductivity of the films is robust and rather insensitive to the variations of the band position and effective mass caused by the substitution of Se by Te. However, the band gap between the electron- and hole-like bands at the Brillouin zone center decreases towards band inversion and parity exchange, which drive the system to a nontrivial topological state predicted by theoretical calculations. Our results provide a clear experimental indication that the FeTe 1− x Se x monolayer materials are high-temperature connate topological superconductors in which band topology and superconductivity are integrated intrinsically. [ABSTRACT FROM AUTHOR]