Microwave emission from spin centres in carbon-based materials
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2023-10-22 |
| Authors | Alberto Ghirri |
| Institutions | Istituto Nanoscienze |
Abstract
Section titled āAbstractāIsolated spin centres dispersed in nonmagnetic host materials are characterized by discrete energy levels with splittings that typically lie in the microwave range of frequency. While the excitation of spin transitions by absorption of microwave photons is pivotal in spectroscopic and manipulation techniques based on magnetic resonance, nonradiative decay through phonon-induced relaxation is intrinsically dominating over radiative decay, typically hampering the emission of microwaves. Thanks to the Purcell effect, the spontaneous emission of photons can be enhanced by placing the spins in a resonant cavity. Furthermore, in well-defined conditions the stimulated emission beyond the masing threshold can also be achieved by pumping the spin transitions with microwave or visible radiation to create a population inversion. Here, I will first review recent progresses in the development of room-temperature masers to discuss future directions and possible applications. I will then describe the characterization of novel organic materials, in particular picene films and crystals doped with pentacene molecules [1, 2], and their possible application as maser gain media. I will finally report recent experiments carried out with nitrogen-vacancy centres in diamond in low mode volume three-dimensional and planar resonators aimed at increasing the conversion efficiency and the emitted microwave power.