Cavity magnonics with van der Waals antiferromagnet*

Cavity magnonics with van der Waals (vdW) materials is of recent interest for application in hybrid quantum architecture. We study magnon-photon coupling in a cavity magnonics device based on chromium trichloride (CrCl3), a vdW antiferromagnet, and a coplanar waveguide (CPW) resonator made of niobium nitride (NbN). Intrinsic disorder of NbN helps in preserving high Q against vortex induced losses in a magnetic field. [1] Below Neel temperature, CrCl3 shows two antiferromagnetic resonance (AFMR) modes and several spin wave modes. [2] In a combined system of CrCl3 and NbN resonator, we observe magnon-photon coupling between these modes and the cavity. [1] We report magnon-photon coupling strengths to have an order of magnitude close to the mode frequencies themselves for the AFMR modes. Since excitation and intermodal coupling of the AFMR modes depend on field symmetry, the magnitude and direction of the field provide additional tunability to the hybrid modes. A complex mode dispersion, high magnon-photon coupling strength, magnetic field tunability, and resonance frequencies at GHz make this promising for application in hybrid devices at microwave regime.