Ab initio studies of chiral phonons

Typically, a single phonon mode realizes vibration related to linear
motion. However, in the presence of n-folded (n>2) rotational symmetry,
the phonon wavefunction possesses additional (geometric) phase, which
allows for the realization of chiral phonons by single, non-degenerate
phonon branches, i.e. circular motion of the atoms around the
equilibrium positions. Previous theoretical studies demonstrated that
chiral phonons can be found in ideal two-dimensional hexagonal lattices
[1,2]. Here, I will present our results of ab initio studies of the
chiral phonons in several compounds, such as CoSn-like systems (with
P6/mmm symmetry, and containing both kagome and honeycomb sublattices)
[3], magnetic topological insulators TBi2Te4 (T=Mn,Fe) [4], binary
compounds ABi (A=K,Rb,Cs) containing chiral Bi chains [5], and
orthorhombic ternary YAlSi compound [6].

References

[1] L. Zhang and Q. Niu, Phys. Rev. Lett. 115, 115502 (2015).
[2] H. Chen, W. Wu, S. A. Yang, X. Li, and L. Zhang, Phys. Rev. B 100,
094303 (2019).
[3] A. Ptok, A. Kobiałka, M. Sternik, J. Łazewski, P. T. Jochym, A. M.
Oleś, S. Stankov, and P. Piekarz,
Phys. Rev. B 104, 054305 (2021).
[4] A. Kobiałka, M. Sternik, and A. Ptok,  Phys. Rev. B 105, 214304
(2022).
[5] J. Skórka, K.J. Kapcia, P.J. Jochym, and A. Ptok, Matter. Today
Commun. 35, 105888 (2023).
[6] S. Basak and A. Ptok, Crystals 12 , 436 (2022).