Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session L22: Electrons, Phonons, ElectronPhonon Scattering and Phononics IIIFocus

Hide Abstracts 
Sponsoring Units: DCOMP DMP Chair: Lucas Lindsey Room: BCEC 157C 
Wednesday, March 6, 2019 11:15AM  11:51AM 
L22.00001: Electronphonon coupling and electronic transport in ntype PbTe: Insights from first principles calculations Invited Speaker: Ivana Savic Exploiting the fascinating properties of materials near soft mode phase transitions is an emerging concept in the quest to increase thermoelectric efficiency [1]. Soft phonons may lead to low lattice thermal conductivity, while preserving high electronic conductivity. Here I will focus on the unusual electronic transport properties of ntype PbTe, which is a classic thermoelectric material that exists near a soft optical mode phase transition. Our first principles calculations show that longitudinal optical phonon scattering dominates electronic transport, while acoustic phonon scattering is relatively weak [2,3]. We find that scattering due to soft transverse optical phonons is by far the weakest scattering mechanism, due to the symmetryforbidden scattering between the conduction band minima and the zone center soft modes [3]. Soft phonons thus play the key role in the high thermoelectric figure of merit of ntype PbTe: they do not degrade its electronic transport properties although they strongly suppress the lattice thermal conductivity [1]. 
Wednesday, March 6, 2019 11:51AM  12:03PM 
L22.00002: Predictive calculations of phononlimited carrier mobilities in semiconductors Samuel Ponce, Elena Roxana Margine, Martin Schlipf, Feliciano Giustino In this talk, we will probe the accuracy limit of ab initio calculations of carrier mobilities that relies on the electronphonon coupling, within the framework of the Boltzmann transport equation. In particular, we will show that predictive calculations of electron and hole mobilities require manybody quasiparticle corrections to band structures and electronphonon matrix elements, the inclusion of spinorbit coupling, and an extremely fine sampling of inelastic scattering processes in momentum space [1]. 
Wednesday, March 6, 2019 12:03PM  12:15PM 
L22.00003: Stochastic properties of a hot electron gas in a semiconductor from firstprinciples Alexander Choi, Austin Minnich Recent advances in abinitio methods have enabled the routine calculation of the electronic transport properties of crystals. Analogous calculations of stochastic properties, such as the spectral noise power of an electron gas driven by an electric field, have not yet been reported despite their importance in setting fundamental detection limits of microwave electronics. Here, we report an abinitio treatment of the noise of a driven electron gas using a BoltzmannGreen’s function approach. Our approach combines electronic structure and scattering rates from firstprinciples with a numerically exact solution of the Boltzmann equation, providing a parameterfree description of stochastic transport processes in a semiconductor. The insights derived our abinitio approach will facilitate the realization of semiconductor devices operating near the quantum noise limit. 
Wednesday, March 6, 2019 12:15PM  12:27PM 
L22.00004: Probing electronphonon interactions in Weyl semimetal using Raman spectroscopy and anharmonic phonon calculations Kunyan Zhang, Fei Han, ShunLi Shang, ZiKui Liu, Mingda Li, Shengxi Huang TaP, a type of Weyl semimetal (WSM) with noncentrosymmetric space group I4_{1}md, is a special type of quantum materials that have attracted strong recent interests. The gapless band structure of TaP allows unique optical response and transport phenomena. Although electrical and photoemission characterizations such as Hall measurement and angleresolved photoemission spectroscopy (ARPES) have been performed on various WSMs, there is insufficient research on the electronic and optical properties using optical spectroscopies as probes. In the present work, the lightmatter interactions, including electronphonon and electronphoton interactions, have been studied comprehensively through phononbased Raman spectroscopy and firstprinciples calculations. We demonstrate how the optical spectroscopic responses, such as Raman and absorption, of TaP change under various physical parameters including crystal orientation, temperature, and excitation laser energies. Advanced firstprinciples calculations of electronic and especially anharmonic phonon properties have been employed to unveil the measured optical spectroscopic responses and their relationship with electronic performance of WSMs. 
Wednesday, March 6, 2019 12:27PM  12:39PM 
L22.00005: High Temperature Charge Transport In Strontium Titanate Clement Collignon, Benoit Fauque, Kamran Behnia Strontium titanate quickly becomes metallic upon doping, but while the fermiology of this metallic phase is well understood its transport properties remain elusive [1]. 
Wednesday, March 6, 2019 12:39PM  12:51PM 
L22.00006: Band structure and optical properties of boron arsenide (BAs): effects of quasiparticle corrections, spinorbit coupling, and phononassisted optical transitions Kyle Bushick, Kelsey Mengle, Nocona Sanders, Emmanouil Kioupakis The IIIV semiconductor BAs is best known for its high thermal conductivity, which was computationally predicted and recently experimentally validated. However, due to a lack of highquality samples, the electronic and optical properties have not been systematically explored. We use density functional and many body perturbation theory including quasiparticle and spinorbit coupling corrections to systematically characterize the electronic and optical properties of BAs. Accurate calculations of band gap values, carrier effective masses, and dielectric functions yield insights into the fundamental properties of this new material. We further explore the effect of phononmediated transitions across the indirect band gap on the optical properties. We will discuss the implications of our findings on potential applications of BAs to semiconductor technologies. 
Wednesday, March 6, 2019 12:51PM  1:03PM 
L22.00007: Ab initio studies of electronphonon coupling to the electron selfenergy in organic crystals Florian BrownAltvater, Gabriel Antonius, Tonatiuh Rangel Gordillo, Matteo Giantomassi, Claudia Draxl, Xavier Gonze, Steven G. Louie, Jeffrey B Neaton Organic crystals combine properties of individual molecules and extended periodic systems. They garner much scientific interest due to their high charge carrier mobilities, and because their unique electronic and vibrational properties challenge our understanding of fundamental optoelectronic processes. In this work we use density functional perturbation theory to study the phononscattering lifetimes, as well as the temperature dependence of the band structure. We find that a selfconsistent approach to the electron selfenergy due to electronphonon coupling yields qualitative differences compared to a conventional approach, and shows much better agreement with experimental results. We discuss efficient methods for selfconsistency in organic crystals, and implications on calculating band gap renormalization and quasiparticle lifetimes of these systems. 
Wednesday, March 6, 2019 1:03PM  1:15PM 
L22.00008: Ab initio exciton and phonon dynamics in Transition Metal Dichalcogenides Pedro Melo, Matthieu Verstraete, Zeila Zanolli The interest in the properties of transition metal dichalcogenides (TMDs) has increased due to the discovery of the coupling between spin and valley degrees of freedom, which can be seen experimentally using a circularly polarised laser. After excitation the newly formed carrier populations must move towards the other valley until balance is reached. However, this relaxation process is not entirely understood in the literature, where the relative importance of the electronelectron (ee) or electronphonon (ep) interactions is still a subject of debate. Previous works on WSe_{2} [A. MolinaSánchez, et al  Nano letters, 2017] have shown that the ep interaction is a good candidate to describe the relaxation process. Using a fully abinitio framework based on the BaymKadanoff equations [P. M. M. C. de Melo and A. Marini, Phys. Rev. B 93, 155102 (2016)] we study the influence of the ep interaction on MoSe_{2} after its excitation by a laser field. We show how phonons allow carrier relaxation and how the Kerr signal and total magnetisation are affected at different temperatures, with the latter exhibiting a nonmonotonic behaviour as the temperature increases. 
Wednesday, March 6, 2019 1:15PM  1:27PM 
L22.00009: Ab Initio Electronic T_{1} Spin Relaxation Times in Silicon and Diamond Jinsoo Park, JinJian Zhou, Marco Bernardi Spin relaxation in inversionsymmetric crystals primarily occurs through the ElliottYafet mechanism, in which the injected spins are scattered by impurities at low temperatures and phonons at higher temperatures. We present an efficient firstprinciples approach for computing the phononlimited ElliottYafet electronic spin relaxation time T_{1} in materials ranging from metals to semiconductors and insulators. Our scheme combines fullyrelativistic ab initio electronphonon scattering with a novel approach to correctly treat Kramers degenerate electronic states. Application of our approach to silicon and diamond is discussed in this talk, where we analyze the temperature dependence of the spin relaxation times together with the contributions from intravalley and intervalley processes. The computed spin relaxation times in silicon are in excellent agreement with experiment above 50 K. Our work enables accurate ab initio calculations of the T_{1} spin relaxation time in a range of materials, including topological ones, providing new microscopic insight into spin relaxation. 
Wednesday, March 6, 2019 1:27PM  1:39PM 
L22.00010: Quantumkinetic theory for electrondiffusion and phonondrag thermoelectric powers from drifting electrons in a quantum wire Richard Zhang, Danhong Huang Thermal conditions during an ultrafast femtosecondscale laser pulse are difficult to resolve due to phonon vibration drag behind an electron excitation. The motivation behind this study is to establish a groundup quantum dynamics model to predict elastic wave effects in a confined electronphonon state. We established transient collision equations from threephonon coupled anharmonic interactions to obtain the evolution of hot phonon species distribution and thermoelectric response in a confinedsize semiconductor material, such as a GaAs nanowire subjected to a spatially uniform DC electric field. A simplified diatomic chain model was chosen to represent longitudinal phonon dispersion. A quasisteady state was observed in electronphonon driftdrag response and settling of low frequency phononphonon scattering. We also studied the effects from phononsurface boundary parameters, such as fluctuation strength and interaction length. As new materials with surprising measured transport properties are being found, further development of this unifying theory of carrierlattice dynamics has potential for capturing ephemeral excitations in various solids. 
Wednesday, March 6, 2019 1:39PM  1:51PM 
L22.00011: Electronphonon coupling from ab initio linearresponse theory within the GW method: Method and applications to oxide superconductors Zhenglu Li, Gabriel Antonius, Meng Wu, Felipe Da Jornada, Steven G. Louie We present a firstprinciples linearresponse theory of changes due to perturbations in the quasiparticle selfenergy operator within the GW method. This approach, named GW perturbation theory (GWPT), is applied to calculate the electronphonon (eph) interactions with the full inclusion of the GW nonlocal, energydependent selfenergy effects, going beyond densityfunctional perturbation theory. Unlike the frozenphonon approach, GWPT gives access to eph matrix elements at the GW level of all phonons, and the computational cost scales linearly with the number of phonon modes (wavevectors and branches) investigated. We present results of correlationenhanced superconductivity in Ba_{0.6}K_{0.4}BiO_{3} and of eph physics in other oxide superconductors where manyelectron effects are strong. 
Wednesday, March 6, 2019 1:51PM  2:03PM 
L22.00012: Firstprinciples study of electronphonon interactions in SrTiO3 Nikolaus Kandolf, Carla Verdi, Feliciano Giustino

Wednesday, March 6, 2019 2:03PM  2:15PM 
L22.00013: Excitonphonon interactions in organic crystals from first principles manybody perturbation theory Jonah Haber, Sivan RefaelyAbramson, Gabriel Antonius, Felipe Da Jornada, Steven G. Louie, Jeffrey B Neaton Molecular crystals are attractive candidates for solar energy conversion applications due to their strong lightmatter interactions, nearly endless structural tunability, and the relative inexpense with which they can be synthesized and processed. Acene crystals, such as tetracene and pentacene, possess both strong electronhole and significant electronphonon interactions, and a thorough understanding of the photophysics of these materials requires a careful analysis of the interplay between the ionic and excitonic degrees of freedom. In this talk, we present our linear response framework for computing excitonphonon matrix elements, using ab initio density functional perturbation theory and manybody perturbation theory within the GW plus BetheSalpeter equation approach. We apply this method to compute excitonphonon scattering rates for spinsinglet and spintriplet excitons in prototypical acene crystals and compare with experimental linewidths. Finally, we discuss the implications of our calculations for exciton diffusion and multiexciton generation in these extended organic systems. 
Follow Us 
Engage
Become an APS Member 
My APS
Renew Membership 
Information for 
About APSThe American Physical Society (APS) is a nonprofit membership organization working to advance the knowledge of physics. 
© 2021 American Physical Society
 All rights reserved  Terms of Use
 Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 207403844
(301) 2093200
Editorial Office
1 Research Road, Ridge, NY 119612701
(631) 5914000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 200452001
(202) 6628700