Edge-derived magnetisms in very thin non-doped Bi2Te3 nanomesh

Abstract

Pristine topological insulators (TIs) with no carrier doping principally suffer from a lack of magnetic ordering. We create a nanomesh structure, a honeycomblike array of hexagonal nanopores with extremely high density, on a nondoped two-dimensional (2D) thin TI (Bi2Te3). We observe antiferromagnetism (AFM) in completely hydrogen-terminated nanomeshes, while it is eliminated by ferromagnetism (FM) in completely O-terminated nanomeshes. Interplay between the AFM and FM is observed in partially O-terminated nanomeshes. As a possible origin for the observed magnetisms, Kramers doublets, which may exist around nanopore edges, for AFM and those eliminated by FM spin alignment due to O-Te coupling along pore edges are discussed based on the structure and annealing dependence of the magnetisms. The nondoped 2D nanomesh formed on a TI will lead to new avenues of research on topological magnetisms and spintronics.