Interaction of chiral phonons and spin
Research Project, 2023 – 2026

State-of-the-art experiments with THz laser pulses allow for the excitation of chiral phonons. In contradiction to theory, they uncover the significant sample magnetization due to currently unknown spin-phonon coupling mechanisms.
I aim to close this knowledge gap by developing the microscopic theory for the coupling of chiral phonons to the electron spin and explain the observed giant phonon magnetic moment. Further, I apply this novel spin-phonon coupling theory to complex metal organic framework materials. Here, I investigate the interplay of itinerant electrons and torsional modes of molecular linkers. This opens the prospect of "torsionics" where electron interactions and topology can be switched in a fully controlled manner. The project will be embedded into the research of my own group at Chalmers. The project is carried out by myself and a PhD student in three work packages: i) method development (year 1-2); ii) phonon Zeeman effect (year 2-3); iii) torsionics (year 3-4). I apply a combination of theoretical tools. The concept of the spin-phonon interaction is developed in the framework of the relativistic quantum mechanics in accelerating frames. Estimates in materials and torsionics are obtained by a combination of density functional theory and empirical tight-binding and k.p theory. The latter is developed in the in-house code GTPack. My theory will provide the foundation for pump probe experiments at MAX IV, European XFEL, and ESS as well as new quantum devices.


Matthias Geilhufe (contact)

Chalmers, Physics, Condensed Matter and Materials Theory


Swedish Research Council (VR)

Project ID: 2022-03350
Funding Chalmers participation during 2023–2026


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