Advanced magnetic materials for chiral phonons

• Applicant: Professor Dr. Manfred Albrecht
• Subject Area: Experimental Condensed Matter Physics
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 541503763

Exploration of the physics of chiral phonons for novel kinds of spintronic information sciences requires high-quality materials with selected magnetic properties. We will therefore investigate the growth and physical properties of various magnetic thin film systems. High magnetostrictive as well as low damping thin films will be prepared and employed for various experiments in this Research Unit. In this regard, we will research and develop a general approach to obtain thin membrane films from bulk substrates suitable for ultrafast electron diffraction experiments. The method will rely on epitaxial thin film growth of magnetic materials together with mechanical grinding followed by ion-beam milling. As an alternative route, rare-earth iron garnets (RIGs) with low Gilbert damping and large magnon diffusion length, will be prepared on water-solvable layers allowing to extract free standing RIG membranes. The large variety of materials to be prepared will facilitate the discovery and exploration of the physics of chiral phonons throughout the Research Unit. In a further study, we will utilize surface acustic waves (SAW) carrying phononic angular momentum, showing great potential as a way to control magnetism. In this regard, we will study the impact of the phonon angular momentum of the SAW on the magnetization by characterizing the change in magnetization in dependence of the SAW propagation direction (phononic angular momentum), SAW power, and SAW frequency. The change in magnetization will be characterized by the anomalous Hall effect and SAW transmission measurements. With these studies, we will become able to understand better the role of chiral phonons in hybrid materials in the gigahertz regime on the transfer of phonon angular momentum to the spin system and to establish to what extent it can contribute to the control of magnetization reversal important for applications in spintronic data processing.

• DFG Programme: Research Units
• Subproject of: FOR 5844: Chiral phonons for spintronics_ChiPS