By understanding the compositional boundaries of the Ga-based tetrahelices in the III-VI-VII class of 1D van der Waals helices, a MRSEC team at the University of California, Irvine demonstrated, for the first time, the discovery of a bulk single crystal that features weakly bound helical chains of GaSI which is characterized by a non-natural helical cross section in a “squircle” geometry (hybrid between a square and a circle).
A MRSEC team at the University of California, Irvine has developed a generic neural network kinetics framework to solve diffusion problems in compositionally complex materials (CCMs)—in the process, addressing a long-standing challenge in modeling diffusion and chemical ordering in CCMs.
Intercalation of air-stable monolayer Pb into EG/SiC by confinement heteroepitaxy (CHet) enables study of heavy metal films at the extreme limit of thinness with complementary microscopy and spectroscopy. Pb coverages up to 90% can be achieved at elevated temperatures beyond those of conventional ultrahigh vacuum methods.
AC electric double layer gating (EDL) periodically applies large electric fields to two-dimensional gallium to enable the detection of a permanent dipole moment in the 2D layer, using microreflectivity. This validates predictions that 2D metals will have a dipole resulting from non-centrosymmetric bonding.
High-entropy materials shift the traditional materials discovery paradigm to one that leverages disorder, enabling access to unique chemistries unreachable through enthalpy alone. A MRSEC team at Penn State University has developed a high-throughput framework for discovering and understanding the single-phase formation of high-entropy oxides by integrating computation and experiment in a self-consistent feedback loop. To more rapidly explore rock salt composition space, the team utilizes CHGNet machine-learning interatomic potentials with impressive accuracy even in disordered systems.
Wisconsin MRSEC researchers have demonstrated that strain can dramatically alter the magnetoelastic properties of a two-dimensional material, CrSBr. Magnetoelasticity is the interaction between magnetism and strain. The researchers developed a nanoscale mechanical resonator device to measure the material’s magnetoelastic coupling. Using it, they showed that 2D CrSBr has a particularly large coupling, and that it can be tuned by 50% by stretching the 2D membrane.
Wisconsin MRSEC researchers have developed a new way to see how molecules fit together with an electron microscope. They used the method to see how molecules rearrange when an organic semiconductor is heated. A modest change in temperature creates significantly improved molecular alignment. The improved alignment is reflected in both larger aligned regions and straighter lines of molecules inside each region.
One of the most active research directions of 2D materials research is to explore new quantum phenomena and emergent phases. A major obstacle to the advancement of this direction has been the limited spectroscopic access due to a mismatch in the van der Waals sample sizes (1 – 10 µm) and the large wavelengths (0.1 − 1 mm) of electromagnetic radiation relevant to their low-energy landscape and excitations. This work, carried out by the MRSEC team at Columbia University, now offers a new “van der Waals stacking approach” for exploring direct spectroscopic insight into the low-energy landscape of quantum phases by leveraging the fundamental benefits of van der Waals assembly. More practically, the very efficient THz emitting material that can be integrated on a chip will be of great use for next-generation 6G communications and networking that rely on THz technologies.
The discovery of superconductivity in twisted graphene systems has generated tremendous interest, where low-energy flat bands with strong correlations play a key role. Flat bands may also be induced by moiré patterning in the transition metal dichalcogenides (TMDs), however experimental observation of superconductivity has remained absent. This raises the question as to whether superconductivity is a universal feature in flat-band, two-dimensional systems or there is some unique graphene-specific feature that makes superconductivity favorable.
FORGES is a summer program designed to offer exposure and experience in collegiate-level STEM work to local high school students who are interested in a career or academic pathway in STEM. CHARM partners with University of Delaware departments and industry partners to provide hands-on activities, collegiate and industrial laboratory exposure, and interactions with faculty, students, and staff.
