title: Fractal Lévy Heat Transport in Nanoparticle Embedded Semiconductor Alloys.
abstract: Materials with embedded nanoparticles are of considerable interest for thermoelectric applications. Here, we experimentally characterize the effect of nanoparticles on the recently discovered Lévy phonon transport in semiconductor alloys. The fractal space dimension α ≈ 1.55 of quasiballistic (superdiffusive) heat conduction in (ErAs)x:InGaAlAs is virtually independent of the Er content 0.001 < x < 0.1 but instead controlled by alloy scattering of the host matrix. The increased nanoparticle concentration does reduce the diffusive recovery length by an order of magnitude. The bulk conductivity drops by 3-fold, in close agreement with a Callaway model. Our results may provide helpful hints toward engineering superdiffusive heat transport similar to what has been achieved with light in Lévy glasses.
authors: †Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States.
authors: Amr M S
authors: AM
authors: Mohammed
authors: †Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States.
authors: Yee Rui
authors: YR
authors: Koh
authors: †Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States.
authors: Bjorn
authors: B
authors: Vermeersch
authors: ‡Materials Department, University of California, Santa Barbara, California 93106, United States.
authors: Hong
authors: H
authors: Lu
authors: ‡Materials Department, University of California, Santa Barbara, California 93106, United States.
authors: Peter G
authors: PG
authors: Burke
authors: ‡Materials Department, University of California, Santa Barbara, California 93106, United States.
authors: Arthur C
authors: AC
authors: Gossard
authors: †Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States.
authors: Ali
authors: A
authors: Shakouri
keywords: Ballistic heat transport; Lévy flight; Nanoparticles; Superdiffusion; Thermal Conductivity; Thermoelectric materials