Triplet superconductivity in the Dirac semimetal germanene on a substrate

The success of graphene and its emerging Dirac physics has stimulated the quest for versatile and tunable electronic properties in atomically thin systems, leading to the discovery of various chemical classes of two-dimensional (2D) compounds. In particular, honeycomb lattices of group-IV elements, such as silicene and germanene, have been found experimentally. Whether it is a necessity of synthesis or a desired feature for application purposes, most 2D materials demand a supporting substrate. In this Rapid Communication, by combining ab initio simulations with multiorbital functional renormalization group analysis of Fermi surface instabilities, we highlight the constructive impact of substrates to enable the realization of exotic electronic quantum states of matter, where the buckling emerges as the decisive material parameter adjustable by the commensuration. At the example of germanene deposited on MoS2, an experimentally characterized superstructure, we find that the coupling between the monolayer and the substrate, together with the buckled hexagonal geometry, conspire to provide a highly suited scenario for unconventional triplet superconductivity.