Materials Sciences and Engineering Research Highlights

Frustrated magnetism found in a topological insulator

Frustration can lead to topological magnetic textures, such as skyrmions, that modify the anomalous transport of topological fermions.

The Surface Termination of CsPbBr3 Perovskite Quantum Dots

An atomistic understanding of the QD surface structure will facilitate the development of more environmentally robust QDs.

Nematicity’s impact on spin fluctuations and superconductivity

The role of nematicity on the relationship between AFM fluctuations and superconductivity was discovered in
iron-based superconductor Fe(Se1-xSx) systems.

Graphical depiction of the role of nematicity

3D Assembly of Gold Nanorods

Interplay of temperature, salt concentration, pH, and interpolymer complexation (IPC) provides an unparalleled diverse set of control parameters to assemble nanoparticles and nanostructures

Full-Scale Ab Initio Theory for Dynamic Nuclear Polarization

This advanced theory enables the in silico design of better polarizing agents and DNP matrices. The structure of core-shell materials can now be determined by predicting the spatial distribution of DNP enhancements.

Tuning Electronic Structures through Strain

A 3D representation of magnetoelastoresistance

Diffraction paradox reveals perfection in graphene

A broad diffraction component observed in electron diffraction of graphene reveals the degree of structural perfection. The broadening is due to electron confinement within the graphene layer, with single layer precision over the mesoscale.

$(top) 2-d diffraction pattern of graphene grown on SiC shows sharp spots on a very broad background around the (00) and G(10) spots. (bottom) 1-d scan of the (00) spot along [12 ̅10] shows the broad component with unusually large FWHM that unexpectedly correlates to forming a highly uniform film.$

Competing orders and role of fluctuations in FeSe

Above a critical pressure associated with the onset of magnetic order, superconducting and magnetic fluctuations exist over a wide temperature range above their respective bulk transition temperatures. Superconductivity in FeSe under pressure is bulk and competes with magnetism; measurements reveal fluctuations of superconductivity and magnetism likely due to their competing nature similar to other high-Tc superconductors.

Temperature-pressure phase diagram of FeSe from specific heat measurements.

Probing the Microstructure of Poly(Cyclosilane)

The microstructure of poly(cyclosilane) was determined by 29Si solid-state NMR spectroscopy and density-functional theory calculations. The NMR and DFT calculation structure determination protocol will be useful to resolve the molecular structure of silicon-based materials, enabling structure-function relationships to be established.

(Left) Simplified polymeric microstructures of poly(cyclosilane) consisting of a trans (blue) and cis (red) diastereomer with chair and twisted-boat cyclosilanering conformations. (Right, Top) Natural abundance 2D 29Si double-quantum-single-quantum homonuclear correlation NMR spectrum. (Right, Bottom) Comparison of the experimental and DFT calculated 29Si NMR spectra for both diastereomers

Phase diagram of the van der Waals ferromagnet VI3 under pressure

Van der Waals (vdW) materials are versatile systems for the study of magnetism in low dimensions. Motivated by the potential tunability of the new vdW ferromagnet VI3, a microscopic and thermodynamic study on bulk single crystals were performed under hydrostatic pressure using new techniques developed at Ames Laboratory.