For strongly anisotropic time-reversal invariant (TRI) insulators in two and three dimensions, the band inversion can occur respectively at all TRI momenta of a high symmetry axis plane. Although these classes materials are topologically trivial as strong weak $Z_{2}$ indices trivial, they host an even number unprotected helical gapless edge states or surface Dirac cones on some boundaries. We ...

Iron selenide (FeSe) is an iron-based superconductor which shows unique properties, including strongly anisotropic superconducting gap, paramagnetism in undoped compound, and extremely small Fermi pocket size. In this work, we demonstrate that the sizes of electron hole pockets FeSe monolayer become much smaller than those bulk. The energy on order a few meV can be fine tuned by thickness graph...

Abstract Characterizations of round wires iron-based superconductors were performed by using two different X-ray techniques. The core the wire turns out to be concentrically textured. texturing parameter ( r ) defined = I (002)/ (103) has a clear correlation with value critical current density J c wire. Using ~18 m-long (Ba, A )Fe 2 As : K, Na) wires, small magnets was constructed and successfu...