Topological phononics in crystalline materials
Phonons are the quantized vibration of the crystal lattice that carry heat in insulators and semiconductors and thus the ability of manipulating them is central in many applications, ranging from thermal management, thermoelectricity and ,perhaps the most visionary of them, phonon-based logic and computing. Topological nontrivial phonons have been studied in artificial periodic structures, i.e. phononic crystals, and as intrinsic quantized collective excitations of atomic vibrations at terahertz frequency. The latter are of particular importance and can promote fundamental investigations and promising applications related to phonons, such as dissipationless phonon transport, quantized Hall effect, etc. The goal of this project is to investigate the intrinsic topological phononic states inside realistic crystalline solids and provide recipes for their experimental realization and engineering. The TOPological pHONonics In Crystalline materiALS (TOPHONICALS) project will deliver a framework aimed at designing and realizing nontrivial topological phonon states in realistic crystalline materials, exploring their use in applications related to renewable energy and information technology. Specifically, TOPHONICALS will focus on topological phononic states like quantum anomalous/spin/valley hall-like (Q(A/S/V)H-like) states and Weyl phonons with the purpose to achieve these states in the realistic materials, so that thermal devices such as dissipationless phonon waveguides, phonon diodes, negative refraction materials can be further designed and engineered. The challenge and novelty of TOPHONICALS is delivering a set of recipes to realize these devices not simply using theoretical models but realistic materials. This approach would allow us to imagine a low power phononic circuits, highly efficient phonon valley filters and an ideal phonon diode, as the topological phononic states are promising one-way boundary states immune to scattering.