Direct observation of phonon Anderson localization in Si/Ge aperiodic superlattices

Hu, Renjiu; Tian, Zhiting

doi:10.1103/physrevb.103.045304

Cited by 37 publications

(25 citation statements)

References 32 publications

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“…Important progress was made to explicitly demonstrate the phonon localization by the thermal conductivity maximum of periodic SLs with randomly embedded nanodots 34 , which has been experimentally observed recently 41 . The decrease of thermal conductivity with total length is attributed to the exponential decay of phonon transmission to zero [32][33][34] , which is more directly evidenced in a recent modal-level NEGF 3 study of randomly aperiodic SLs 35 . The phonon localization in aperiodic SLs in the presence of anharmonicity and interfacial mixing is thoroughly studied by MD simulation 38 , where the thermal conductivity maximum appears at a sufficient level of periodicity disorder.…”

Section: Introductionmentioning

confidence: 80%

“…As the level of disorder in the graded SLs is moderate compared to the random disorder (e.g. in aperiodic SLs 35,38 ), a strong localization 42 cannot be reached and the ballistic transport wins out at Np ≥ 4 ~ 5. As a comparison, the thermal conductivity maximum reported in the strong localization regime 34,35,38,41 results from the ballistic-to-localized transition as the system length increases to be comparable to and larger than the phonon localization length.…”

Section: Thermal Conductivity Minimummentioning

confidence: 99%

“…in aperiodic SLs 35,38 ), a strong localization 42 cannot be reached and the ballistic transport wins out at Np ≥ 4 ~ 5. As a comparison, the thermal conductivity maximum reported in the strong localization regime 34,35,38,41 results from the ballistic-to-localized transition as the system length increases to be comparable to and larger than the phonon localization length. The present minimum is also different from the previous thermal conductivity minimum 13,[15][16][17] due to the coherent-to-incoherent transition when increasing the period length of SLs under a fixed total length.…”

Section: Thermal Conductivity Minimummentioning

confidence: 99%

“…The phonon transmission and localization in disordered SLs systems were studied based on elastic continuum models in the low-frequency limit [29][30][31] . The influence of phonon localization on thermal transport properties has been more extensively explored by atomistic simulation methods via either ballistic non-equilibrium Green's function (NEGF) [32][33][34][35] or molecular dynamics (MD) [36][37][38][39][40] . The localization effect was shown to be not observable in thermal conductivity of isotope-disordered nanotubes due to the small contribution of highfrequency localized phonons at temperatures low enough to preserve phonon coherence from anharmonic scattering 32,33 .…”

Section: Introductionmentioning

confidence: 99%

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Thermal conductivity minimum of graded superlattices due to phonon localization

et al. 2021

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The Anderson localization of thermal phonons has been shown only in few nanostructures with strong random disorder by the exponential decay of transmission to zero and a thermal conductivity maximum when increasing system length. In this work, we present a path to demonstrate the phonon localization with distinctive features in graded superlattices with short-range order and long-range disorder. A thermal conductivity minimum with system length appears due to the exponential decay of transmission to a non-zero constant, which is a feature of partial phonon localization caused by the moderate disorder. We provide clear evidence of localization through the combined analysis of the participation ratio, transmission, and real-space phonon number density distribution based on our quantum transport simulation. The present work would promote heat conduction engineering by localization via the wave nature of phonons.

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Section: Introductionmentioning

confidence: 80%

Section: Thermal Conductivity Minimummentioning

confidence: 99%

Section: Thermal Conductivity Minimummentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermal conductivity minimum of graded superlattices due to phonon localization

et al. 2021

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“…In his seminal paper, disordered defects in the potential landscape cause multiple scattering of electron waves, resulting in spatially localized electronic states. Since it is a consequence of the wave nature, Anderson localization is broadly applicable to both quantum mechanical waves defined by the Schrödinger equation and classical wave systems, such as acoustics, elastics, electromagnetics, and optics [62][63][64][65][66][67][68]. Among various classical wave realizations, Anderson localization of light has attracted tremendous attention due to mature experimental tools to probe the localization phenomena and diverse possibilities to construct disordered "optical potentials" using disordered refractive index distributions [69][70][71][72].…”

Section: Anderson Localizing Disordered Optical Fiber Historical Review On the Origin Of Alofmentioning

confidence: 99%

Learning-Based Image Transport Through Disordered Optical Fibers With Transverse Anderson Localization

Zhao

Gausmann

et al. 2021

Front. Phys.

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Fiber-optic imaging systems play a unique role in biomedical imaging and clinical practice due to their flexibilities of performing imaging deep into tissues and organs with minimized penetration damage. Their imaging performance is often limited by the waveguide mode properties of conventional optical fibers and the image reconstruction method, which restrains the enhancement of imaging quality, transport robustness, system size, and illumination compatibility. The emerging disordered Anderson localizing optical fibers circumvent these difficulties by their intriguing properties of the transverse Anderson localization of light, such as single-mode-like behavior, wavelength independence, and high mode density. To go beyond the performance limit of conventional system, there is a growing interest in integrating the disordered Anderson localizing optical fiber with deep learning algorithms. Novel imaging platforms based on this concept have been explored recently to make the best of Anderson localization fibers. Here, we review recent developments of Anderson localizing optical fibers and focus on the latest progress in deep-learning-based imaging applications using these fibers.

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Temperature Tunable Anderson Localization and Metal–Insulator Transition of Acoustic Waves in High‐Entropy Phononic Crystal

et al. 2023

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Inspired by the electrical insulators made by high‐entropy alloys, this work studies the feasibility of using a 2D high‐entropy phononic crystal (PnC) to achieve Anderson localization within its first transmission band. The entropy of sound increases proportionally with the increase of additional eigenmodes at a certain frequency which decreases the transmitted energy through the structure. 2D disorder in sizes (or) and materials of the scatterers is introduced to achieve that on a perfect periodic PnC designed with metallic scatterers in an ambient water‐based lattice medium. Around the band edge of the first transmission band, Anderson's localization of sound is discovered. At a resonant frequency within a perfect periodic crystal, the introduction of a disorder in the PnC results in an exponential decay of sound wave transmission along the propagation direction due to the entropy generation from acoustic energy. Furthermore, the temperature tunability of the proposed crystal is proposed. A variation of the room temperature to 0 °C leads to the phase transition of water to ice and results in a strong transition of the acoustic localization at resonant frequencies with a 25 dB+ difference.

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Direct observation of phonon Anderson localization in Si/Ge aperiodic superlattices

Cited by 37 publications

References 32 publications

Thermal conductivity minimum of graded superlattices due to phonon localization

Thermal conductivity minimum of graded superlattices due to phonon localization

Learning-Based Image Transport Through Disordered Optical Fibers With Transverse Anderson Localization

Temperature Tunable Anderson Localization and Metal–Insulator Transition of Acoustic Waves in High‐Entropy Phononic Crystal

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