Interaction of chiral phonons and spin

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.