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This IRG focuses on the mechanical behavior of disordered materials, particularly beyond the onset of yield. The Figure shows recent advances in using Machine Learning (ML) methods to characterize the local structural environment of disordered materials with respect to susceptibility for particulate rearrangements using a quantity called softness. (A-D) shows an analysis of a polycrystalline material (created via Molecular Dynamic simulations) using ML and the concept of softness [1]. The Figure shows that softness (bright spots in D) is able to capture rearrangements measured as shown by colored particles in (C). This approach correctly identifies crystalline and grain boundary regions as having low values and high variability of softness, respectively. We also extended the concept of softness to anisotropic particles [2] (E). Similar predictive performance to isotropic particles is observed and a recursive feature elimination (RFE) method is introduced to better understand how softness arises from particular structural aspects that can be systematically tuned e.g. by particle aspect ratio.  Indeed, longer particles lead to different global flow patterns for a pillar under compression (F).

The Illinois MRSEC developed and implemented an 8-week program called “Musical Magnetism” that engages middle school students in materials science using the popular platform of music. The program combines engaging lessons and demos, researching a topic, turning that research into lyrics, and recording a song. 35 8th graders at Franklin STEAM Academy participated.

The new NU-MRSEC REU+ Program enables select REU participants from small colleges to follow their summer experience with an academic quarter at Northwestern University as domestic exchange students, thereby allowing them to experience the rigor of an R1 university in a nurturing environment. REU+ students take classes and also continue their research for an additional ten weeks.

A recent study introduces new ways to analyze ultrafast-light-driven magnetic structures that show simultaneous demagnetization and emit THz radiation. Historically, little work has been done to calculate THz emissions from these systems. The researchers developed two new methods that combine advanced theories to predict a new phenomenon of charge current pumping due to ultrafast demagnetization. This research enhances our understanding of the interactions within these materials, opening up potential for future applications in spintronics and terahertz technologies.

Cornell scientists have found that thin films of SrRuO3, when optimally produced, have an exceptionally high spin Hall ratio. This is directly correlated with the degree that octahedral RuO6 subunits in the crystal are tilted away from a flat in-plane orientation.

An important goal in electronics is to reduce power use without sacrificing performance. In spintronics this can be accomplished by increasing the rate of charge to spin conversion. We show that one of the most efficient means of converting charge to spin information uses a topological insulator and voltages instead of currents.  

At the University of Chicago MRSEC, we have constructed active liquid droplets comprised of the biopolymer actin, crosslinker and molecular motors myosin. The motors spontaneously divide the droplets in half.

To enhance drop formation, a team at the Harvard MRSEC led by Lewis created a new printing method that relies on generating sound waves to assist gravity, dubbing this new technique acoustophoretic printing.

Precise control over defects in materials is often a highly effective means to control properties and function. In oxide materials, which are the focus of enormous current attention for many existing and proposed applications, defects known as oxygen vacancies often play the key role. These vacancies, simply missing oxygen atoms in the structure, can have a significant impact on properties.

We discovered a new hexagonal metallic antiferromagnetic phase in the Cu-Mn-As system.   Electrical switching and read-out of tetragonal CuMnAs inspired a world-wide research effort in metallic antiferromagnets. Phase equilibria in this system (Fig. a) however is poorly understood.