Single-layer transition metal dihalides grown on conducting substrates were shown to host stable polarons. Here, we investigate polarons in insulating single-layer MnBr2 grown by molecular beam epitaxy on three different substrates, namely graphene on Ir(110), graphene on Ir(111), and Au(111). The number densities and species of polarons observed vary strongly as a function of the substrate. For MnBr2 grown on Ir(110) the largest number of polaron species is observed, namely four, of which three show clear similarities with the species observed for CoCl2 on graphite. Polarons in single-layer MnBr2 are observed up to 300K. They can be created, converted, and moved by the STM tip when a tunneling current flows at a proper bias voltage. For graphene on Ir(110) as a substrate, mobile polarons in MnBr2 are guided through the periodic potential imposed from the super-moir\'e resulting from the interaction of MnBr2 with graphene and Ir(110). Our findings indicate that modeling of polarons in such single-layer insulators in contact with a conducting substrate requires to take the substrate explicitly into account.
@article{arxiv.2512.21163,
title = {Substrate Role in Polaron Formation on Single-layer Transition Metal Dihalides},
author = {Affan Safeer and Oktay Güleryüz and Guangyao Miao and Wouter Jolie and Thomas Michely and Jeison Fischer},
journal= {arXiv preprint arXiv:2512.21163},
year = {2025}
}