Ultrafast Optical Control of Spins in Antiferromagnet-TMDC Heterostructures

• Applicants: Dr. Hamoon Hedayat Zadeh Roodsari; Professor Dr. Paul H. M. van Loosdrecht
• Subject Area: Experimental Condensed Matter Physics
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 563196881

Antiferromagnets (AFM) have emerged as promising candidates for future information transmission due to their ability to support spin waves or magnons at terahertz frequencies. This property enables fast and energy-efficient information transfer. However, the optical control of magnons in AFM materials remains a significant challenge. Recent studies have demonstrated that the control and excitation of magnons in AFM materials are possible through various mechanisms, such as resonance excitation, orbital splitting of band transitions, and non-resonant processes like impulsive stimulated Raman scattering. The goal of this project is to explore the efficient optical control of magnons in antiferromagnet-transition metal dichalcogenide heterostructures (AFM-TMDC-HS). Specifically, we investigate the strong coupling between AFM magnons and TMDC excitons. We plan to utilize the selective excitation of valley-spin-polarized excitons and analyze their interaction with magnons in monolayer AFM magnets. To characterize interlayer interactions, we will conduct a set of complementary ultrafast spectroscopy techniques, including transient absorption, time-resolved micro-Raman spectroscopy (TR-μRaman), and time-resolved magneto-optical spectroscopy, to study ultrafast charge transfer and exciton-magnon interactions in AFM-TMDC-HS. Additionally, we will employ ultrafast optics, layer twisting, and external fields to manipulate and control magnons in these heterostructures. The project focuses on two main aspects: (a) Control of magnons through the injection of hot valley-spin-polarized carriers: We investigate the dynamics of excitons and the injection of hot electrons after photoexcitation to optimize the control of hot carrier transfer. (b) Coupled dynamics of magnons and excitons, including Moiré-magnon-excitons: We explore magnon dynamics, induce magnetic oscillations, and analyze the interactions between magnons and TMDC excitons, particularly in the presence of Moiré-magnon-excitons and twisted stacked layers. For the time- and frequency-resolved investigation of these processes, we will utilize transient absorption, time-resolved micro-Raman spectroscopy, and time-resolved magneto-optical spectroscopy. These comprehensive investigations aim to provide valuable insights into the dynamics and interactions of magnons and excitons in AFM-TMDC-HS, ultimately paving the way for ultrafast and precise optical control of magnetization dynamics.

• DFG Programme: Research Grants