Near-field optical characterization techniques of twisted and indirectly nanostructured 2D material heterostructures
- Abstract number
- 360
- Corresponding Email
- [email protected]
- Session
- Stream 4 (AFM): Functional Scanning Probe Microscopy for Advanced Material Science
- Authors
- Prof Frank Koppens (1)
- Affiliations
-
1. ICFO
- Keywords
Near-field
2D materials
Graphene
Twistronics
Infrared
Terahertz
Photocurrent
- Abstract text
Two-dimensional (2D) materials offer extraordinary potential for control of light and light-matter interactions at the atomic scale. In particular, twisted 2D materials has recently attracted a lot of interest due to the capability to induce moiré superlattices and discovery of electronic correlated phases [1,2]. In this talk, we present nanoscale optical techniques such as near-field optical microscopy and photocurrent nanoscopy, and reveal with nanometer spatial resolution unique observations of the optical properties of twisted 2D materials. We report on the topological domain wall boundaries [4] of small-angle twisted graphene and interband collective modes in charge neutral twisted-bilayer graphene near the magic angle [3]. The freedom to engineer these so-called optical and electronic quantum metamaterials [1] is expected to expose a myriad of unexpected phenomena.
As an example for indirectly patterned polaritons, we introduce and demonstrate a novel multimodal reflection mechanism of the ray-like optical excitations in hyperbolic materials, such as hBN. Using near-field microscopy, we observe mid-IR confinement in BIC-based nanocavities with volumes down to 23x23x3 and quality factors above 100 – a dramatic improvement in several metrics of confinement.
- References
[1] Song, Gabor et. al., Nature Nanotechnology (2019)
[2] Cao et al., Nature (2018)
[3] Hesp et al., Arxiv 1910.07893
[4] Hesp et al., Nature Communications (2020)
[5] Epstein et al., Science (2020)
[6] Herzig Sheinfux et al., (2021