PhD: RF Circulators Based on 3D Cavity Magnonics

Phd in co-tutelle between IMT Atlantique (Brest, 2 years) and UWA QDM lab (Perth, 1 year) Funding: COFUND SEED (https://www.imt-atlantique.fr/en/research-innovation/phd/seed) Domain and scientific/technical context: Cavity magnonics is an emerging research field that investigates light-matter interactions within magnetism, specifically the interactions between cavity photons and magnons, the quanta of spin waves based on the magnetic dipole interaction. At the core of cavity magnonics are cavity-magnon polaritons (CMPs) which are the associated bosonic quasiparticles to hybridized cavity magnon-photon states in the strong coupling regime. Cavity magnonics kicked off theoretically in 2010 and shortly after experimentally with the demonstration of CMPs both in the quantum regime at millikelvin (mK) temperatures and in the classical regime at room temperature (RT). Due to the broad range of applicability and underlying fundamental physics from quantum to classical systems, it has attracted broad interest from various research communities . Novel magnon-based devices (such as transducers, quantum memories and logics) may provide an efficient information processing platform. Targeted scientific and technical problems: Microwave circulators are typically composed of a Y-junction transmission line and ferrite materials. However, they are usually treated as a simple black box in experiments, where their internal modes involving spin excitations exhibit too much loss and are too complex to be analyzed. In addition, most of these devices suffer from a lack of tunability (working frequency and bandwidth). Hybrid systems that couple two or more dynamic excitations are a promising solution to obtain the missing functionality. CMPs can be engineered by chiral excitation to build nonreciprocal devices. The interaction with chiral microwave photons follows a selection rule: only magnons and photons of the same chirality interact with each other, while the interaction of magnons and photons of opposite chirality is forbidden. Here, the system, represented by three coupled harmonic oscillators, will be used to achieve nonreciprocity with isolation better than 50 dB.