A theoretical framework predicts the emergence of non-reciprocal interactions that effectively violate Newton’s third law in solids using light, report researchers from Japan. They demonstrate that by irradiating light of a carefully tuned frequency onto a magnetic metal, one can induce a torque that drives two magnetic layers into a spontaneous, persistent “chase-and-run” rotation. This work opens a new frontier in non-equilibrium materials science and suggests novel applications in light-controlled quantum materials.

Geiger-mode avalanche photodiodes (APDs) are capable of detecting single photons by harnessing a process called avalanche multiplication. 4H-SiC APDs have demonstrated high sensitivity in the deep ultraviolet range. However, at higher wavelengths of light, APDs require advanced architectures to improve their unity-gain quantum efficiency to maintain single-photon sensitivity. Optimizing avalanche photodiodes for high wavelength operation brings several design challenges. Researchers have now created a numerical model with a calibrated 4H-SiC material library for designing avalanche photodiodes for near-ultraviolet photodetection.