Publications by authors named "Matthew Cothrine"
Surface plasmon polaritons (SPPs) provide a window into the nano-optical, electrodynamic response of their host material and its dielectric environment. Graphene/α-RuCl serves as an ideal model system for imaging SPPs since the large work function difference between these two layers facilitates charge transfer that hole dopes graphene with ∼ 10 cm free carriers. In this work, we study the emergent THz response of graphene/α-RuCl heterostructures using our home-built cryogenic scanning near-field optical microscope.
View Article and Find Full Text PDFTwo-dimensional semiconductors, such as transition metal dichalcogenides, have demonstrated tremendous promise for the development of highly tunable quantum devices. Realizing this potential requires low-resistance electrical contacts that perform well at low temperatures and low densities where quantum properties are relevant. Here we present a new device architecture for two-dimensional semiconductors that utilizes a charge-transfer layer to achieve large hole doping in the contact region, and implement this technique to measure the magnetotransport properties of high-purity monolayer WSe.
View Article and Find Full Text PDFQuantum oscillations evidence for topological bands in kagome metal ScVSn.
J Phys Condens Matter
February 2024
Article Synopsis
- - Metals with a kagome lattice, like the newly discovered VSn, are interesting because they can have both flat-band and Dirac electronic structures.
- - The study examines ScVSn, using quantum oscillations in electrical transport and magnetization to investigate its electronic properties, which align with theoretical models.
- - Findings show a significant Berry phase for a key orbit, providing evidence of a topological band structure and enhancing understanding of the complex physics in kagome metals.
The integration time and signal-to-noise ratio are inextricably linked when performing scanning probe microscopy based on raster scanning. This often yields a large lower bound on the measurement time, for example, in nano-optical imaging experiments performed using a scanning near-field optical microscope (SNOM). Here, we utilize sparse scanning augmented with Gaussian process regression to bypass the time constraint.
View Article and Find Full Text PDFArticle Synopsis
- - The study explores the electronic properties of a graphene and α-ruthenium trichloride (α-RuCl) heterostructure, which may have significant implications for next-gen optoelectronic devices due to α-RuCl being a Mott insulator and Kitaev material.
- - Using advanced techniques like photoemission spectroscopy and low-energy electron microscopy, researchers visualize charge transfer between graphene and α-RuCl, altering the electronic characteristics of both materials at their interface.
- - The findings highlight the strong interaction between graphene and α-RuCl, suggesting potential new methods to manipulate electronic properties in 2D materials, crucial for developing low-power electronic applications.
Article Synopsis
- The study explores the use of work-function-mediated charge transfer for controlling the electrostatics of individual atomic layers, using α-RuCl as a 2D electron acceptor next to hexagonal boron nitride (BN).
- It highlights how this arrangement induces unique nano-optical behavior in BN by causing interlayer charge polarization, resulting in a reduction of phonon polariton (PhP) propagation length significantly beyond intrinsic losses.
- The findings are backed by advanced techniques like scattering-type scanning near-field optical microscopy and first-principles calculations, demonstrating the promising applications of charge-transfer heterostructures in enhancing the optoelectronic properties of 2D insulators.
We demonstrate ultrasharp (≲10 nm) lateral p-n junctions in graphene using electronic transport, scanning tunneling microscopy, and first-principles calculations. The p-n junction lies at the boundary between differentially doped regions of a graphene sheet, where one side is intrinsic and the other is charge-doped by proximity to a flake of α-RuCl across a thin insulating barrier. We extract the p-n junction contribution to the device resistance to place bounds on the junction width.
View Article and Find Full Text PDFThe ability to create nanometer-scale lateral p-n junctions is essential for the next generation of two-dimensional (2D) devices. Using the charge-transfer heterostructure graphene/α-RuCl, we realize nanoscale lateral p-n junctions in the vicinity of graphene nanobubbles. Our multipronged experimental approach incorporates scanning tunneling microscopy (STM) and spectroscopy (STS) and scattering-type scanning near-field optical microscopy (s-SNOM) to simultaneously probe the electronic and optical responses of nanobubble p-n junctions.
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