Localized surface electromagnetic waves in CrI$_3$-based magnetophotonic structures

TL;DR

This paper investigates localized surface electromagnetic waves in CrI$_3$-based structures, revealing their properties through ab initio calculations and exploring conditions for surface plasmon polariton generation and resonance.

Contribution

It provides the first detailed analysis of surface electromagnetic waves in CrI$_3$-based structures using ab initio conductivity data, including critical angle estimates and multilayer configurations.

Findings

Surface plasmon polaritons can be generated in CrI$_3$ structures.

The critical angle for plasmon excitation depends on layer thickness.

Surface plasmon resonance is achievable at the CrI$_3$-air interface.

Abstract

Resulting from strong magnetic anisotropy two-dimensional ferromagnetism was recently shown to be stabilized in chromium triiodide, CrI$_3$, 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 CrI$_3$-based structure using the results of {\it ab initio} calculations for the CrI$_3$ 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 CrI$_3$ layer thicknesses. We also study the bilayer structure formed by two CrI$_3$ layers separated by a SiO$_2$ spacer and show that the surface plasmon resonance can be achieved at the interface between CrI$_3$ and air depending on the spacer thickness.