Materials Sciences and Engineering Research Highlights

The Surface Structure of Semiconductor Nanoparticles Revealed

By mixing precipitated nanoparticles (NP) with boron nitride (BN) a 9-fold improvement in DNP NMR sensitivity was realized compared to established DNP protocols. This new protocol enables challenging 2D NMR experiments that reveal the structure and connectivity of atoms in a variety of semiconductor NP systems.

(Top) Schematic structure of a semiconductor nanoparticle showing the crystalline core region, the surface region and capping ligands. (Lower) The impregnated powder procedure described in this work yields 9-fold better DNP NMR sensitivity than the previously described impregnated support procedure.

Direct imaging of unstained DNA origami

DNA origami was deposited and directly imaged using scattering transmission electron microscopy, with spatial resolution adequate for detecting key nanometer-scale structural details. This work presents proof-of-concept results demonstrating that electron microscopy can be used to resolve key elements of DNA-based structures without the use of staining protocols.

Tailor Plasmons in Pentacene/Graphene Heterostructures with Interlayer Electron Transfer

Van der Waals (vdW) heterostructures, which are produced by the precise assemblies of varieties of two-dimensional (2D) materials, have demonstrated many novel properties and functionalities. Here we report a nanoplasmonic study of vdW heterostructures that were produced by depositing ordered molecular layers of pentacene on top of graphene.

Dynamic Nuclear Polarization Using Radicals Created by γ-Irradiation

γ-irradiation induced the formation of stable radicals that were used to polarize 29Si and 1H spins in inorganic and organic solids by dynamic nuclear polarization (DNP). γ-irradiation will enable magic angle spinning (MAS) DNP experiments on previously inaccessible non-porous inorganic solids and insoluble polymers.

Interplay between magnetism and superconductivity probed by controlled disorder

Introducing disorder through electron irradiation simultaneously suppresses the magnetic and superconducting transition temperatures. The effects of non-magnetic disorder reveals the non-trivial influence of non-magnetic disorder on coupled superconductivity and magnetism in iron based superconductors.

Squeezed Nanocrystals

We have developed and validated a model which predicts size-independent shapes of metal nanoparticles that are supported on a solid surface and blanketed by a two-dimensional material such as graphene.

Manipulating Coherent Transport in Topologically Protected Surface States

Topology-protected charge transport on surfaces of three-dimensional topological insulators (TIs) is breaking new ground in quantum science and technology.

Ab Initio Simulation of DNP Enhancements

Accelerating the discovery of improved polarizing agents through simulation requires a proper treatment of the concerted dynamics of thousands of spins over several seconds, far exceeding conventional approaches incorporating only a handful of spins. This was achieved by restricted state space methods and a Monte Carlo optimization algorithm to calculate the enhancements directly, without worrying about the timescale of the interactions. This new approach enabled the calculation of DNP enhancements in systems containing upwards of 50 spins allowing for the importance of the spin diffusion and the diffusion barrier to be determined.

Simple stress criterion for navigating phase transformations

Lattice instability criterion is linear in stresses for any stress state in a material.

New Quantum Criticality Discovered in Superconductivity

Understanding the link between magnetism and unconventional superconductivity remains a grand challenge in quantum materials. Significant progress gaining deeper insight into this challenge has been made via the first observation of a quantum criticality (QC) with a hedgehog spin-vortex crystal antiferromagnetic state.