Control of Spin Transition and Resonance by Chiral Phonons

Chiral phonons possessing angular momentum are closely associated with phonon modes that exhibit circular lattice vibrations. When considering chiral phonons in organic chiral materials, the interactions between the phonon angular momentum and the spin angular momentum are highly diverse. In this study, organic chiral enantiomers are prepared with different chiral asymmetry factors. Chiral phonons are observed using a circularly polarized Raman setup. As the asymmetry factor decreases, the chiral phonons gradually disappear. The coupling between the angular momentum of the chiral phonons and the electron spins becomes more pronounced at larger asymmetry factor values. Furthermore, the electrons present a broader array of pathways to enhance recombination, satisfying the principle of conservation of angular momentum. In addition, the electron spin resonance signals of the chiral samples exhibit differential responses to left- and right-handed circularly polarized light with identical intensities. Overall, chiral phonons with nonzero angular momentum in chiral systems are strongly coupled with electron spins to modulate effectively the spin transition and spin resonance, thereby enhancing the potential application of chiral phonons in optophononic-spintronic devices.