SPICE Workshop on Ferrons and Magnons: friends or foes? July 7th - 9th, 2026
Marcos Guimarães
Van der Waals (vdW) materials are ideal systems for the study optical study of magnons in low dimensions since they maintain their excellent optical, magnetic and electronic properties down to the atomically-thin limit. Because of their low dimensionality, these materials possess another exciting property, they are extremely sensitive to external stimuli, such as light and electric fields.
In this talk, I will show how we can reveal excitonic features and study the magnetization dynamics of a van der Waals magnetic semiconductor – Cr2Ge2Te6 (CGT) – using (time-resolved) magneto-optics. First, I will discuss our recent results[1] on the magneto-optic Kerr effect (MOKE) spectroscopy in CGT, which shows a very strong magneto-optic response arising from excitonic effects. The excitonic fingerprint on the MOKE spectrum of CGT is further confirmed by ab-initio calculations. Using electrostatic gating, we demonstrate the control of the magneto-optic efficiency of CGT, allowing us to modulate the MOKE signals by up to 65%. I will also discuss our recent work on the control of magnetization dynamics in CGT using electrostatic gating[2]. By exploiting opto-magnetic phenomena, we are able to excite magnetization dynamics using ultrafast laser pulses and control, both the excitation process and the dynamics, using electrostatic doping and electric fields. Finally, time allowing I will present recent results on the propagation and interaction of excitons and magnons in another van der Waals magnet – CrSBr – in the limit of high exciton and magnon densities.
Our studies illustrate the potential of van der Waals magnets for combining ultrafast optics and magnetism, making them appealing for the study of magnons in low dimensions and for the development of new opto-spintronic and opto-magnonic devices.
F. Hendriks, et al., Phys. Rev. Materials 10, L011001 (2026).
F. Hendriks, et al., Nature Communications 15, 1298 (2024).