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.
