Highlights
Orientation control of epitaxial transition metal dichalcogenides on hexagonal boron nitride via defects
In two recent 2DCC publications, joint experimental and theory efforts identified a general method to achieve orientational selectivity, originating from a localized defect pair that amplifies the energetic distinction between the two orientations.
An integrated quantum material testbed with multi-resolution photoemission spectroscopy
Professor Shuolong Yang group at the University of Chicago has set up a new integrated platform for multiresolution photoemission spectroscopy (MRPES) that integrates a helium discharge lamp, a narrow bandwidth 6 eV laser, and a tunable ultrafast laser, which effectively combines static ARPES, time-resolved ARPES (trARPES), and micro-ARPES (μARPES).
Fingerprinting 2-Dimensional Polar Metals
In this highlight, we identified newly discovered low-frequency (LF) (<100 cm−1 ) Raman features due to the formation of unique 2D polar metals (Ag, Cu, Pb, Bi, Ga, In) or metal alloys (InxGa1−x) intercalated at an epitaxial graphene (EG)/silicon carbide (SiC) interface and demonstrate that 2D-Ag and 2DGa can have spatially distinct phases with their own unique Raman responses. Additionally, we establish that the 2D-Ga exhibits a structural evolution as a function of temperature, independent of the SiC and EG, that can lead to nucleation of secondary phases.
Dual-sided Adsorption onto 2D
When an atomically thin 2D material is suspended as a membrane so that adsorbed atoms can stick to both sides, these atoms can interact through the membrane and thus act as two coupled adsorbate systems, with new properties that are absent in either system alone. Computational modeling in the 2D Crystal Consortium predicts new patterns that emerge, such as an infinite staircase of fractional coverages of opposing sides with simple rational fractions being favored, a so-called “Devil’s Staircase.”
Scalable Substitutional Re-Doping and its Impact on the Optical and Electronic Properties of Tungsten Diselenide
Doping is the cornerstone of semiconductor technology, enabling the success of modern digital electronics. Successful realization of wafer-scale, electronic grade, intrinsic 2D TMDCs via common deposition methods is rapidly progressing, however, advances in scalable doping still remain in the “proof-of-concept” stage, delaying the large-scale fabrication of logic circuits based on extrinsic 2D semiconductors. This work is presenting a wafer-scale synthesis of rhenium doping of WSe2 films via MOCVD at front-end-of-line (FEOL) and back-end-of-line (BEOL) compatible temperatures.
Multiphysics Model and Application Development for Controlled 2D Materials Growth
This review provided an overview of theoretical, computational, and machine learning methods and tools at multiple length and time scales, and how they can be utilized to assist/guide the design and synthesis of 2D materials. It focuses on three methods at different length and time scales.
Scientific Travel Extension Program For Outreach Representatives Working to Advance Research Diversity (STEPFORWARD)
STEPFORWARD is a geospatial tool built on Google Maps API to identify minority serving institutions (MSIs), primarily undergraduate institutions (PUIs) and non-R1 institutions within a geographical radius of travel. Higher Education R&D data highlights institutions active in research fields of interest. The tool enables 2DCC researchers and the broader community to identify a diverse range of institutions for outreach visits and research interactions. The 2DCC supports visits to these institutions as part of a travel extension program.
Studying the influence of a capping layer on interfacial superconductivity in FeSe/SrTiO3 heterostructures
Understanding the superconductivity at the interface of FeSe/SrTiO3 is a problem of contemporary interest in condensed matter physics because of the significant increase in the critical temperature (Tc ~ 50 K) for the onset of superconductivity compared to that of bulk FeSe crystals (Tc ~ 9 K). Additional interest in this problem arises from the possibility of an unconventional pairing mechanism. We used the 2DCC multimodule molecular beam epitaxy (MBE) and surface characterization facility to study the influence of various capping layers on the Tc of ultrathin films of FeSe grown on SrTiO3.
Stochastic Resonance In MoS2 Photodetector
In this project, we use a novel approach for next generation ultra-low-power sensor design by embracing the evolutionary success of animals with extraordinary sensory information processing capabilities that allow them to survive in extreme and resource constrained environments.
Evidence of 2D Room-temperature Magnetic Semiconductors
Dilute magnetic semiconductors, achieved through substitutional doping of magnetic atoms into semiconducting systems, enable experimental modulation of spin dynamics for novel magneto-electric or magneto-optical devices, especially in 2D transition metal dichalcogenides that accentuate interactions and activate valley degrees of freedom.
Topological Hall Effect in Topological Insulator/Magnetic Insulator Bilayer
The topological Hall effect (THE) is a phenomenon that is a consequence of a Berry phase created by spin textures in real space. Interfacing a topological insulator with a magnetic insulator provides a model platform for studying this phenomenon in a well-controlled manner. This paper reports the first clear evidence for the THE in heterostructures that combine a model topological insulator (Bi2Se3) with a ferromagnetic insulator (BaFe12O19).
Wafer scale epitaxial growth of unidirectional WS2 monolayers on sapphire
Realization of wafer-scale single-crystal films of transition metal dichalcogenides (TMDs) such as WS2 requires epitaxial growth and coalescence of oriented domains to form a continuous monolayer. The domains must be oriented in the same crystallographic direction on the substrate to inhibit the formation of inversion domain boundaries (IDBs), which form when oppositely oriented triangular domains coalesce.
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