2020/03/31 by Xianxin Wu, Wladimir A. Benalcazar, Yinxiang Li +3 · 1 citation
Physics and Astronomy · #cond-mat.supr-con #cond-mat.mes-hall #cond-mat.str-el
paper · pdf · doi:10.1103/physrevx.10.041014
published as Phys. Rev. X 10, 041014 (2020) · 8 pages, 4 figures + supplementary materials
arxiv created 2020/11/08 · arxiv updated 2020/11/10
Non-trivial topology and unconventional pairing are two central guiding principles in the contemporary search for and analysis of superconducting materials and heterostructure compounds. Previously, a topological superconductor has been predominantly conceived to result from a topologically non-trivial band subject to intrinsic or external superconducting proximity effect. Here, we propose a new class of topological superconductors which are uniquely induced by unconventional pairing. They exhibit a boundary-obstructed higher-order topological character and, depending on their dimensionality, feature unprecedently robust Majorana bound states or hinge modes protected by chiral symmetry. We predict the 112-family of iron pnictides, such as Ca1-xLaxFeAs2, to be a highly suited material candidate for our proposal, which can be tested by edge spectroscopy. Because of the boundary-obstruction, the topologically non-trivial feature of the 112 pnictides does not reveal itself for a bulk-only torus band analysis without boundaries, and as such had evaded previous investigations. Our proposal not only opens a new arena for highly stable Majorana modes in high-temperature superconductors, but also provides the smoking gun evidence for extended s-wave order in the iron pnictides.