Exploring dynamics, disorder, and anharmonicity in THz spectra of crystalline materials

Terahertz spectral measurements of crystalline materials are known to be particularly sensitive to both the material’s long-range order and lattice dynamics. Here we explore a range of materials including common crystalline organic materials such as α-lactose monohydrate and l-cysteine through to engineered materials including topological insulators (Bi₂(Te(₁₋ₓ)Seₓ)₃) where structure and disorder can be more finely controlled. By comparing variable temperature THz spectral measurements to ab-initio simulations using a range of methods and structures we can begin to unpick the origins of these spectra, and how they are influenced by dynamics and disorder across the lattice.