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Abstract Two-dimensional van der Waals materials such as graphene present an opportunity for band structure engineering using custom superlattice potentials. In this study, we demonstrate how self-assemblies of magnetic iron-oxide (Fe3O4) nanospheres stacked on monolayer graphene generate a proximity-induced magnetic superlattice in graphene and modify its band structure. Interactions between the nanospheres and the graphene layer generate superlattice Dirac points in addition to a gapped energy spectrum near the K and K′ valleys, resulting in magnetic confinement of quasiparticles around the nanospheres. This is evidenced by gate-dependent resistance oscillations, observed in our low temperature transport measurements, and confirmed by self-consistent tight binding calculations. Furthermore, we show that an external magnetic field can tune the magnetic superlattice potential created by the nanospheres, and thus the transport characteristics of the system. This technique for magnetic-field-tuned band structure engineering using magnetic nanostructures can be extended to a broader class of 2D van der Waals and topological materials.
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Homologous Self‐Assembled Superlattices: What Causes their Periodic Polarity Switching?
Abstract Quantum semiconductor structures are commonly achieved by bandgap engineering, which relies on the ability to switch from one semiconductor to another during their growth. Growth of a superlattice is typically demanding technologically. In contrast, accumulated evidence points to a tendency among a certain class of multiple‐cation binary oxides to self‐assemble spontaneously as superlattice structures. This class is dubbed the homologous superlattices. For a famous example, when a mixture of indium and zinc is oxidized, the phases of In‐O and ZnO separate in an orderly periodic manner, along the ZnO polar axis, with polarity inversion taking place between consecutive ZnO sections. The same structure is observed when the indium is replaced with other metals, and perhaps even in ZnO alone. This peculiar self‐assembled structure is attracting research over the past decade. The purpose of this study is to gain understanding of the physics underlying the formation of this unique structure. Here, an explanation is proposed for the long‐standing mystery of this intriguing self‐assembly in the form of an electrostatic growth phenomenon and a test of the proposed model is carried out on experimental data.
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- Award ID(s):
- 2240388
- PAR ID:
- 10641782
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Physics Research
- Volume:
- 3
- Issue:
- 2
- ISSN:
- 2751-1200
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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