Anderson Localization Quenches Thermal Transport in Aperiodic Superlattices
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We show that aperiodic superlattices exhibit intriguing interplay between phononic coherent wave interference effects and incoherent transport. In particular, broadband Anderson localization results in a drastic thermal conductivity reduction of 98% at room temperature, providing an ultralow value of 1.3 W m-1 K-1, and further yields an anomalously large thermal anisotropy ratio of ∼102 in aperiodic Si/Ge superlattices. A maximum in the thermal conductivity emerges as an unambiguous consequence of phonon Anderson localization at a system length scale bridging the extended and localized transport regimes. The frequency-resolved picture, combined with our lattice dynamical description of Anderson localization, elucidates the rich transport characteristics in these systems and the potential of correlated disorder for sub- to few-THz phononic engineering of heat transport in thermoelectric applications.
|Number of pages||6|
|Journal||Physical Review Letters|
|Publication status||Published - 12 Mar 2019|
|MoE publication type||A1 Journal article-refereed|