Terahertz Time Domain Polarimetry for Verification of Chiral Phonons in 2d Perovskites*

Chirality as a physical property in materials emerges from asymmetrical structures that are not superimposable on their mirror images. This asymmetry affects how materials absorb differently polarized light. Recently, chirality has impacted the study of phonons in semiconducting materials such as 2d hybrid organic-inorganic perovskite materials, which can inherit chirality from chiral organic molecules used in their framework. Collective lattice vibration within chiral semiconducting materials have been found to exist with frequencies on the scale of terahertz (THz) and are theorized to be chiral themselves. These chiral phonons can be studied and verified through a technique called THz time-domain polarimetry that measures the polarization states of THz frequency light pulses over time. This verification is important for characterizing the Chiral-Inducted Spin Selectivity Effect where chiral molecules preferentially transmit electrons with specific spin orientations and could thus be used to produce some of the first room temperature spintronic devices with no magnets. Previous work has been successful in demonstrating spectral inversion of THz absorption between enantiomers. We present our results and the efforts to extend these methods to semiconducting materials for verification of chiral phonons.