Search for: All records

The manipulation of coupled quantum excitations is of fundamental importance in realizing novel photonic and optoelectronic devices. We use electroluminescence to probe plasmon–exciton coupling in hybrid structures consisting of a nanoscale plasmonic tunnel junction and few-layer two-dimensional transition-metal dichalcogenide transferred onto the junction. The resulting hybrid states act as a novel dielectric environment that affects the radiative recombination of hot carriers in the plasmonic nanostructure. We determine the plexcitonic spectrum from the electroluminescence and find Rabi splittings exceeding 50 meV in the strong coupling regime. Our experimental findings are supported by electromagnetic simulations that enable us to explore systematically and in detail the emergence of plexciton polaritons as well as the polarization characteristics of their far-field emission. Electroluminescence modulated by plexciton coupling provides potential applications for engineering compact photonic devices with tunable optical and electrical properties. 

A plastic may degrade in response to a trigger. The kinetics of degradation have long been characterized by the loss of weight and strength over time. These methods of gross characterization, however, are misleading when plastic degrades heterogeneously. Here, we study heterogeneous degradation in an extreme form: the growth of a crack under the combined action of chemistry and mechanics. An applied load opens the crack, exposes the crack front to chemical attack, and causes the crack to outrun gross degradation. We studied the crack growth in polylactic acid (PLA), a polyester in which ester bonds break by hydrolysis. We cut a crack in a PLA film using scissors, tore it using an apparatus, and recorded the crack growth using a camera through a microscope. In our testing range, the crack velocity was insensitive to load but was sensitive to humidity and pH. These findings will aid the development of degradable plastics for healthcare and sustainability. 

Spin-orbit coupling (SOC) is a relativistic effect, where an electron moving in an electric field experiences an effective magnetic field in its rest frame. In crystals without inversion symmetry, it lifts the spin degeneracy and leads to many magnetic, spintronic, and topological phenomena and applications. In bulk materials, SOC strength is a constant. Here, we demonstrate SOC and intrinsic spin splitting in atomically thin InSe, which can be modified over a broad range. From quantum oscillations, we establish that the SOC parameter α is thickness dependent; it can be continuously modulated by an out-of-plane electric field, achieving intrinsic spin splitting tunable between 0 and 20 meV. Unexpectedly, α could be enhanced by an order of magnitude in some devices, suggesting that SOC can be further manipulated. Our work highlights the extraordinary tunability of SOC in 2D materials, which can be harnessed for in operando spintronic and topological devices and applications.