Magnetic materials are vital in technologies from spintronics to biomedicine. Coupling magnetism with optical responses broadens their utility to sensing, magneto-optical memory, and optical isolation. Chromium chalcogenide spinels display particularly rich magnetism and magneto-optical properties. Colloidal nanocrystals (NCs) offer routes to solution-processing, heterointegration, and property modulation through size, shape, or heterostructure control, but many chalcogenide spinels have never been synthesized at the nanoscale, and little control over size or morphology has been demonstrated.

Grain boundaries, interfaces between two crystals inside a material, are important defects which can dramatically alter material response because the structure of the boundary is different from the bulk crystalline region.

  Metallic glasses (MGs) are an exciting class of materials due to a suite of attractive properties including high strength, large stretchability, high wear and corrosion resistance, and excellent magnetic properties. However, adoption of MG in many applications has been hindered by the fact that they are brittle: they can break apart very suddenly, especially when put under tension. Ductility – the ability to softly stretch without breaking – would be a better property to have.

In 2015, the MRSEC led the development of an outreach course at Brandeis for Waltham High School students to strengthen our engagement with the WHS community. The course was structured to teach the students biochemistry using 3D molecular models, hands-on activities, CAD, and 3D printing. The class sessions were taught by graduate student and postdoc instructors who received extensive one-on-one curriculum-development mentoring by the

Weyl particles – massless particles linearly dispersing in all three dimensions (3D) -- were first theorized by Hermann Weyl in 1929, who found such a solution to the Dirac equation proposed by Paul Dirac in 1928. A material hosting Weyl particles features singular points in its dispersion relations – the Weyl points. Weyl points are 3D upgrades of the 2D Dirac points in graphene, the proposal of which led to a Nobel prize in Physics in 2010. However, there has been no observation of the Weyl points (particles) until 2015.

Stacking various atomically-thin crystals on top of one another can strongly modify their overall properties. When two materials are stacked with a twist angle, a geometric interference pattern (a moiré pattern) emerges. At special twist angles, the moiré pattern can result in new electronic states dominated by strong correlations between electrons.

IRG-2 has established the controlled tip-based absorption (writing) and desorption (deleting) of hydrogen on C/Si/Ge/Sn graphene materials at atomic length scales. This allows new explorations on the effect of spatial patterns on a 2D material on the electronic transport properties in an ultraclean environment.