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Breaking Rayleigh's law with spatially correlated disorder to control phonon transport
Controlling thermal transport in insulators and semiconductors is crucial for
many technological fields such as thermoelectrics and thermal insulation, for
which a low thermal conductivity () is desirable. A major obstacle for
realizing low materials is Rayleigh's law, which implies that acoustic
phonons, which carry most of the heat, are insensitive to scattering by point
defects at low energy. We demonstrate, with large scale simulations on tens of
millions of atoms, that isotropic long-range spatial correlations in the defect
distribution can dramatically reduce phonon lifetimes of important
low-frequency heat-carrying modes, leading to a large reduction of --
potentially an order of magnitude at room temperature. We propose a general and
quantitative framework for controlling thermal transport in complex functional
materials through structural spatial correlations, and we establish the optimal
functional form of spatial correlations that minimize . We end by
briefly discussing experimental realizations of various correlated structures
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