Relation of Continuous Chirality Measure to Spin and Orbital Polarization, and Chiroptical Properties in Solids

Chirality introduces intriguing topological, electronic, and spin-optronic properties to molecules and solids. In this work, we provide a quantitative metric for the degree of chirality in solids, independent of the type of system and the dimensionality, through the continuous chirality measure (CCM). We quantitatively analyze the correlation between CCM and spin and orbital angular momentum (OAM) polarization, as well as circular dichroism (CD) and the circular photogalvanic effect (CPGE). By internal spin-orbit field analysis, we demonstrate a distinct character (proportionality among Rashba, Deresselhaus, and Weyl contributions) and chirality dependence among different chiral solids. Furthermore, unlike CD, we found that absorption dissymmetry factor $g_{CD}$ could remain unchanged as a function of chirality and show anisotropic dependence on CCM. In addition, we show that the relation between CCM and CPGE is rather complex. At low excitation energy close to the bandgap transition, the CCM continuously tunes the total SOC, and therefore, the CPGE response. However, at high excitation energy, CPGE includes more than just band edge transitions, which complicates the relation of chirality and CPGE due to changes in the optical dipole strength and electron-hole group velocity difference. Ultimately, this causes CPGE to be only correlated with chirality at excitation energies close to the band edge. At the end, we discussed strategies of manipulating chiral-optical properties through chirality transfer at interfaces or applying strain. The insights developed in this work will inspire the design of materials for future spintronics and orbitronics, as well as spin-optronics applications.