Seongshik Oh1
Rutgers Univ1
It is challenging to grow an epitaxial four-fold compound superconductor (SC) on six-fold topological insulator (TI) platform due to stringent lattice-matching requirement. Here, we demonstrate that Fe(Te,Se) can grow epitaxially on a TI (Bi<sub>2</sub>Te<sub>3</sub>) layer as well as magnetic MnTe due to accidental, uniaxial lattice match, which is dubbed as “hybrid symmetry epitaxy”. This new growth mode is critical to stabilizing robust superconductivity with <i>T<sub>C</sub></i> as high as 13 K. Furthermore, the superconductivity in this system survives in Te-rich phase with Se content as low as x = 0.03 but vanishes at Se content above x = 0.56, exhibiting a phase diagram that is quite different from that of the conventional Fe(Te,Se) systems. This unique heterostructure platform that can be formed in both TI-on-SC and SC-on-TI sequences opens a route to unprecedented topological heterostructures. Furthermore, this result opens another possibility of combining topological superconductivity of Fe(Te,Se) with the rich physics of topological magnetism in the (MnTe)<sub>n</sub>(Bi<sub>2</sub>Te<sub>3</sub>)<sub>m</sub> family, a recently emerging platform as intrinsic (anti)ferromagnetic topological insulators.