Spin-dependent Optical Excitations in LiFeO₂

The three-dimensional ternary LiFeO₂ compound presents various unusual properties. The main features are thoroughly explored by using many-body perturbation theory. The concise physical/chemical picture, the critical spin polarizations, and orbital hybridizations in the Li-O and Fe-O bonds are clearly examined through geometric optimization, quasi-particle energy spectra, spin-polarized density of states, spatial charge densities, spin-density distributions, and strong optical responses. The unusual optical transitions cover various frequency-dependent absorption structures, and the most prominent plasmon modes are identified from the dielectric functions, energy loss functions, reflectance spectra, and absorption coefficients. Optical excitations are anisotropic and strongly affected by excitonic effects. The close combinations of electronic, magnetic, and optical properties allow us to identify the significant spin polarizations and orbital hybridizations for each available excitation channel. The lithium ferrite compound can be used for spintronic and photo-catalysis applications.