Search

A collaboration between the University of Chicago MRSEC groups of Jaeger, Patel, and Rowan showed that the complex modulus of a dense suspension of microparticles can be increased exponentially over several orders of magnitude by applying interval training during oscillatory shear, leading to a structural memory. 

Small (nanometer-sized) crystals of multi-component, complex metal oxides have useful properties for applications in electronics, optics, sensors, and mechanical actuators. In order to realize this potential, engineers need to be able to put tiny crystals exactly where they are needed and to control the orientation of the crystal’s lattice.

Semiconductors, which have electrical properties in between metals and insulators, are the building blocks of devices like transistors that fuel computer technology. New semiconducting materials that could outperform existing ones are continuously sought in science and engineering, with oxides being one contender. In recent work in the University of Minnesota MRSEC, researchers studying one such oxide semiconductor - barium tin oxide - made the startling discovery of a completely new type of “line defect”.

The Cleland and Schuster groups at the University of Chicago have demonstrated multi-bit entanglement in a Quantum Network.

Shenoy group in the IRG led a study on the multiaxial behavior of collagen networks. When stretched, the network models exhibited drastic contractions transverse to the direction of loading (yellow arrows in the top left image). The networks exhibited an anomalous Poisson effect, with apparent Poisson’s ratios larger than 1. Experiments validated this result and showed increases of apparent Poisson’s ratio with decreasing collagen concentration (top right image).

PCCM celebrated its annual Holiday Lecture 2020: A Materials Wonderland: A Celebration of How Materials Science Make Our Holidays Fun with PCCM faculty, research members and others providing (virtual) materials science presentations. The audience helped with experiments and demonstrations from their homes. 426 families registered, some with multiple children (tuning from all over the world), resulting in ~1,000 attendees!

Soil is a highly disordered granular material. Slow soil deformation (creep) controls the shape of hills in the natural landscape, and is a precursor of catastrophic landsliding. Our work demonstrates a surprising observation: an apparently static sandpile, sitting on a table, is actually alive with motion. We study a 3D granular heap, confined by walls and prepared by pouring. Via Diffusive Wave Spectroscopy (DWS), we observe the existence of spatially-heterogeneous micro-deformations that decay in size and frequency as time progresses but persist up to 11 days after the preparation of the system; the heap relaxes. We find that this relaxation can be enhanced  (overaged) or reversed (rejuvenated) by tuning the types of disturbances applied to system.

Animal  tissues are composed of cells attached to either the surface of a fibrous network called a basement membrane or embedded within a 3D extracellular or interstitial matrix. As the disease liver fibrosis progresses, the extracellular fibrous networks become denser and more aligned. These physical changes lead to different mechanical properties and structures to which cells are exquisitely sensitive. To better understand the pathological effects of these changes during fibrosis on cells, we have engineered material platforms that mimic the extracellular matrix in tissue health and disease. As an example, we have fabricated fibrous materials that have varied mechanical properties and fiber densities when mechanically loaded due to the chemical adhesion between fibers, similar to natural extracellular matrix (see Figure).

A team at the Harvard MRSEC led by Bertoldi and Aizenberg has developed an approach to achieve a diverse trajectories from a single-material system via self-regulation: when a photoresponsive liquid crystal elastomeric pillar with mesogen alignment is exposed to light, it ‘dances’ dynamically as light initiates a traveling order-to-disorder transition front that twists and bends via opto-chemo-mechanical feedback.

Experimental studies combined with theoretical calculations of spin dynamics across a wide frequency range from ~10 GHz to several THz in a novel amorphous ferromagnet (FM)/3D topological insulator (TI) (FeGaB/BiSb) system that is scalable and provides a promising platform for spin-electronic devices.