Interplay between phonon chirality and electronic topology

• Phonons are important collective excitations in materials. Typically, they do not respond to magnetic field and do not carry a magnetic moment (chirality).
• Phonon chirality can be induced via two mechanisms (i) adiabatic evolution with electronic states that break time-reversal symmetry (e.g. magnetism) and (ii) phonon induced mixing of different electronic energy levels.
• Chiral phonons observed in topological crystalline insulator Pb1-xSnxTe using THz magneto-spectroscopy
• Phonon magnetic moment changed sign across topological phase transition and was two orders of magnitude higher in the topological phase
• Connection between chiral phonons and electronic topology opens new ways to control matter

UT-Austin MRSEC
DMR-1720595