Negative Refraction of Terahertz Phonons via Interfacial Momentum Compensation
arXiv:2511.03599 · doi:10.1103/n9zv-9kc5
Abstract
Negative refraction provides a route to steer and focus wave energy flow, but it remains difficult to realize for coherent terahertz (THz) phonons. The difficulty stems from conventional dispersion-based mechanisms, which require strongly anisotropic or negative-curvature dispersions, while the long-wavelength acoustic phonons most favorable for coherent transport are nearly isotropic. Here we overcome this limitation by introducing a momentum compensation mechanism mediated by discrete translational symmetry. Discrete translational symmetry parallel to the interface supplies a compensating tangential momentum, reopening transmitted channels beyond the conventional critical condition and enabling negative refraction when this compensation reverses the tangential component. Mode-resolved calculations for hBN/graphene heterostructures establish this mechanism in laterally stitched in-plane interfaces and show how twisted van der Waals moire superlattices shift the negative-refraction window to lower frequencies. These results identify periodic crystalline interfaces as symmetry-engineered elements for THz phonon momentum conversion and wavefront control.
arXiv commentAccepted for publication in Physical Review Letters. Revised to match the accepted manuscript; the title, author list, text, figures, and references have been updated
References in corpus (19)
- Moire bands in twisted double-layer graphene
- Distribution of phonon lifetime in Brillouin zone
- Phononics: Manipulating heat flow with electronic analogs and beyond
- Optimized Tersoff and Brenner empirical potential parameters for lattice dynamics and phonon thermal transport in carbon nanotubes and graphene
- Wavefront Modulation and Subwavelength Diffractive Acoustics with an Acoustic Metasurface
- Assessment of the Thermal Conductivity of BN-C Nanostructures
- Topological negative refraction of surface acoustic waves in a Weyl phononic crystal
- Elastic metamaterials with simultaneously negative effective shear modulus and mass density
- Negative Refraction and Left-handed electromagnetism in Microwave Photonic Crystals
- Observation of negative refraction of Dirac fermions in graphene
- Gate-tunable negative refraction of mid-infrared polaritons
- Negative refraction in hyperbolic hetero-bicrystals
- Terahertz phonon engineering with van der Waals heterostructures
- Atomistic S-matrix method for numerical simulation of phonon reflection, transmission and boundary scattering
- Valley filtering effect of phonons in graphene with a grain boundary
- Transmission eigenchannels for coherent phonon transport
- Brillouin zone unfolding method for effective phonon spectra
- Probing the ideal limit of interfacial thermal conductance in two-dimensional van der Waals heterostructures
- Real-Space Visualization of Frequency-Dependent Anisotropy of Atomic Vibrations