Localized surface electromagnetic waves in CrI₃-based magnetophotonic structures

Resulting from strong magnetic anisotropy two-dimensional ferromagnetism was recently shown to be stabilized in chromium triiodide, CrI₃, in the monolayer limit. While its properties remain largely unexplored, it provides a unique material-specific platform to unveil its electromagnetic properties associated with coupling of modes. Indeed, trigonal symmetry in the presence of out-of-plane magnetization results in a non-trivial structure of the conductivity tensor, including the off-diagonal terms. In this paper, we study the surface electromagnetic waves localized in a CrI₃-based structure using the results of ab initio calculations for the CrI₃ conductivity tensor. In particular, we provide an estimate for the critical angle corresponding to the surface plasmon polariton generation in the Kretschmann-Raether configuration by a detailed investigation of reflectance spectrum as well as the magnetic field distribution for different CrI₃ layer thicknesses. We also study the bilayer structure formed by two CrI₃ layers separated by a SiO₂ spacer and show that the surface plasmon resonance can be achieved at the interface between CrI₃ and air depending on the spacer thickness.