Multi-wavelength magnetic coding of helical luminescence in ferromagnetic 2D layered CrI3

TL;DR

This paper demonstrates magnetic control of narrow, multiwavelength helical luminescence in 2D ferromagnetic CrI3 using whispering-gallery modes in microspheres, enabling magnetic encoding for photonic devices.

Contribution

It introduces a simple microsphere cavity approach to strongly couple and control helical emission in 2D ferromagnetic CrI3 at low magnetic fields.

Findings

Reversible magnetic control of multiwavelength helical luminescence.

Narrow emission peaks (~5 nm FWHM) achieved under continuous wave excitation.

Magnetic coding of luminescence in the 950-1100 nm range.

Abstract

Two-dimensional (2D) van der Waals (vdW) ferromagnets have opened new avenues for manipulating spin at the limits of single or few atomic layers, and for creating unique magneto-exciton devices through the coupling of long-range ferromagnetic (FM) orders and excitons. However, 2D vdW ferromagnets explored so far have rarely possessed exciton behaviors; to date, FM CrI3 have been recently revealed to show ligand-field photoluminescence correlated with FM ordering, but typically with a broad emission peak. Alternatively, many-body excitons have been observed in antiferromagnetic (AFM) NiPS3, but the coupling of excitons with AFM orders is exponentially more difficult, owing to extremely high coercivity. Here, we report a straightforward approach to realize strong coupling of narrow helical emission and FM orders at a low magnetic field in CrI3 through a relatively simple microsphere cavity. We show that the resonant whispering-gallery-modes (WGM) of SiO2 microspheres give rising to a series of strong oscillation helical emissions with a full width at half-maximum (FWHM) of ~5 nm under continuous wave excitation. Reversible magnetic control and coding of helical luminescence with multiwavelength is realized in the range of 950-1100 nm. This work enables plenty of opportunities for creating magnetic encoding lasing for photonic integrated chips.