Research Highlights

Honeybees have complex social lives, with their queens and workers cooperating to produce honey. But the majority of bee species are solitary: One female mates, gathers provisions, lays eggs and walls them up with food in a secure spot. Recent UNH research into a mostly solitary species that has some social behaviors, the North American carpenter bee, advances understanding of the evolutionary shift from honeybees’ loner ancestors to the social beings they are now.

For the better part of a decade, engineers have been crafting and testing recipes for so-called van der Waals heterostructures: stacks of atomically thin crystal layers that can be sequenced just so. Compared with a homostructure — the nanoscopic equivalent of a slab of ham — a heterostructure might feature slices of pastrami, pepperoni and pepper jack, all held together by the weak van der Waals forces among neighboring atomic layers.

Engineers soon discovered that the diversity could cultivate technologically interesting properties, often in the regions where two different materials meet, that are otherwise difficult or impossible to recreate. Then, a few years ago, researchers began exploring the effects of rotating the layers within van der Waals stacks. That misalignment of layers, they found, could also yield interesting results — turning a material into a superconductor, for instance, or changing how a semiconductor emits light.

Yet the achievement came in the face of a considerable challenge: Despite the weakness of van der Waals forces, adjacent layers strongly prefer to remain aligned. Manually stacking layers one by one can overcome the issue but demands extreme precision and, more importantly, time that large-scale manufacturers of small-scale technology just don’t have.