Localization of phonons in mass-disordered alloys: A typical medium dynamical cluster approach

Mondal, Wasim Raja; Vidhyadhiraja, N. S.; Berlijn, Tom; Moreno, Juana; Jarrell, Mark

doi:10.1103/physrevb.96.014203

Cited by 15 publications

(10 citation statements)

References 67 publications

(86 reference statements)

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“…The dynamical mean-field theory and its cluster extensions correctly describe the electronic properties of both the R and M 1 phases of VO 2 11,22 . Cluster extension of DMFT such as dynamical cluster approximations (DCA) and its typical medium extension named as typical medium DCA (TMDCA) for disordered phononic systems has been recently developed 23,24 . Unfortunately, such DCA and TMDCA method for phononic systems are currently available for parameter-based model calculations.…”

Section: Introductionmentioning

confidence: 99%

Unraveling the role of V-V dimer on the vibrational properties of VO$_2$ by first-principles simulations and Raman spectroscopic analysis

Mondal,

Evlyukhin,

Howard

et al. 2020

Preprint

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We investigate the vibrational properties of VO2, particularly the low temperature M1 phase by first-principles calculations using the density functional theory as well as Raman spectroscopy. We perform the structural optimization using SCAN meta-GGA functional and obtain the optimized crystal structures for metallic rutile and insulating M1 phases satisfying all expected features of the experimentally derived structures. Based on the harmonic approximation around the optimized structures at zero temperature, we calculate the phonon properties and compare our results with experiments. We show that our calculated phonon density of states is in excellent agreement with the previous neutron scattering experiment. Moreover, we reproduce the phonon softening in the rutile phase as well as the phonon stiffening in the M1 phase. By comparing with the Raman experiments, we find that the Raman-active vibration modes of the M1 phase is strongly correlated with the V-V dimer distance of the crystal structure. Our combined theoretical and experimental framework demonstrates that Raman spectroscopy could serve as a reliable way to detect the subtle change of V-V dimer in the strained VO2.

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Section: Introductionmentioning

confidence: 99%

Unraveling the role of V-V dimer on the vibrational properties of VO$_2$ by first-principles simulations and Raman spectroscopic analysis

Mondal,

Evlyukhin,

Howard

et al. 2020

Preprint

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“…(2) In a related context, are the modes associated with the Boson peak localized or delocalized? (3) As shown in our previous work 18 , lighter isotopic impurities lead to strongly localized, short-wavelength phonons in impurity bands. In this work, we ask whether the effect of FC disorder is to reinforce or negate the localization induced by mass disorder?…”

Section: Introductionmentioning

confidence: 63%

Phonon localization in binary alloys with diagonal and off-diagonal disorder: A cluster Green's function approach

et al. 2019

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We report the development and application of a new method for carrying out computational investigations of the effects of mass and force-constant (FC) disorder on phonon spectra. The method is based on the recently developed typical medium dynamical cluster approach (TMDCA), which is a Green's function approach. Excellent quantitative agreement with previous exact diagonalization results establishes the veracity of the method. Application of the method to a model system of binary mass and FC-disordered system leads to several findings. A narrow resonance, significantly below the van Hove singularity, that has been termed as the boson peak, is seen to emerge for low soft particle concentrations. We show, using the typical phonon spectrum, that the states constituting the boson peak cross over from being completely localized to being extended as a function of increasing soft particle concentration. In general, an interplay of mass and FC disorder is found to be cooperative in nature, enhancing phonon localization over all frequencies. However, for certain range of frequencies, and depending on material parameters, FC disorder can delocalize the states that were localized by mass disorder, and vice-versa. Modeling vacancies as weakly bonded sites with vanishing mass, we find that vacancies, even at very low concentrations, are extremely effective in localizing phonons. Thus, inducing vacancies is proposed as a promising route for efficient thermoelectrics. Finally, we use model parameters corresponding to the alloy system, Ni1−xPtx, and show that mass disorder alone is insufficient to explain the pseudogap in the phonon spectrum; the concomitant presence of FC disorder is necessary. arXiv:1904.05324v2 [cond-mat.dis-nn]

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“…Figure 4 d shows the temperature dependence of the Urbach energy exhibited in all transient component. At low temperature, meV and it increased by % at 300 K. Lattice vibrations and dynamic structural disorder both effect 25 . The former only increases as a function of T due to a growing phonon distribution 26 , whereas dynamic structural disorder can reduce and has been related to the onset of medium-range order, typically in amorphous materials.…”

Section: Resultsmentioning

confidence: 97%

Hot-carrier dynamics in InAs/AlAsSb multiple-quantum wells

Piyathilaka

Sooriyagoda

Esmaielpour

et al. 2021

Sci Rep

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A type-II InAs/AlAs$$_{0.16}$$ 0.16 Sb$$_{0.84}$$ 0.84 multiple-quantum well sample is investigated for the photoexcited carrier dynamics as a function of excitation photon energy and lattice temperature. Time-resolved measurements are performed using a near-infrared pump pulse, with photon energies near to and above the band gap, probed with a terahertz probe pulse. The transient terahertz absorption is characterized by a multi-rise, multi-decay function that captures long-lived decay times and a metastable state for an excess-photon energy of $$>100$$ > 100 meV. For sufficient excess-photon energy, excitation of the metastable state is followed by a transition to the long-lived states. Excitation dependence of the long-lived states map onto a nearly-direct band gap ($$E{_g}$$ E g ) density of states with an Urbach tail below $$E{_g}$$ E g . As temperature increases, the long-lived decay times increase $$<E{_g}$$ < E g , due to the increased phonon interaction of the unintentional defect states, and by phonon stabilization of the hot carriers $$>E{_g}$$ > E g . Additionally, Auger (and/or trap-assisted Auger) scattering above the onset of the plateau may also contribute to longer hot-carrier lifetimes. Meanwhile, the initial decay component shows strong dependence on excitation energy and temperature, reflecting the complicated initial transfer of energy between valence-band and defect states, indicating methods to further prolong hot carriers for technological applications.

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Localization of phonons in mass-disordered alloys: A typical medium dynamical cluster approach

Cited by 15 publications

References 67 publications

Unraveling the role of V-V dimer on the vibrational properties of VO$_2$ by first-principles simulations and Raman spectroscopic analysis

Unraveling the role of V-V dimer on the vibrational properties of VO$_2$ by first-principles simulations and Raman spectroscopic analysis

Phonon localization in binary alloys with diagonal and off-diagonal disorder: A cluster Green's function approach

Hot-carrier dynamics in InAs/AlAsSb multiple-quantum wells

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