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O: Fachverband Oberflächenphysik
O 76: Poster Focus Session Atomic Scale Investigation of Magnetic 2D Materials
O 76.2: Poster
Mittwoch, 19. März 2025, 18:00–20:00, P2
Atomically thin MnBr2 grown by molecular-beam epitaxy on graphene/Ir — Oktay Güleryüz, Affan Safeer, Nicolas Georgopoulos, Thomas Michely, and •Jeison Fischer — II. Physikalisches Institut, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany
We report on the growth of potentially magnetic manganese dibromide (MnBr2) films on graphene/Ir substrates using molecular-beam epitaxy. MnBr2 is evaporated as a single compound from an effusion cell onto the graphene/Ir. Low-electron energy diffraction analysis reveals that the hexagonal lattice constant of MnBr2 amounts to 0.390 ± 0.005 nm, consistent with calculated 0.3885 nm and bulk 0.3873 nm values.
Our scanning tunneling microscopy study reveals that the best growth conditions to form large, compact monolayers involve deposition at elevated temperatures (400 K). Growth at low temperature on graphene/Ir(110) leads to the formation of small islands with a distribution of orientations. A new moiré superstructure is formed, which reflects the interaction of the MnBr2 lattice with the corrugated graphene/Ir(110) moiré.
Low-temperature scanning tunneling spectroscopy at 1.7 K of monolayer MnBr2 further reveals a significant band gap of approximately 5 eV. Additionally, isolated polarons are observed, which can be manipulated, created, and destroyed by the STM tip.
Keywords: magnetic 2D material; manganese dibromide; inert substrate; scanning tunneling microscopy