Phonon-limited resistivity of graphene by first-principle calculations: electron-phonon interactions, strain-induced gauge field and Boltzmann equation
Thibault Sohier, Matteo Calandra, Cheol-Hwan Park, Nicola Bonini, Nicola Marzari, Francesco Mauri
Electron-phonon coupling in graphene is extensively modeled and simulated from first principles. We find that using an accurate model for the polarizations of the acoustic phonon modes is crucial to obtain correct numerical results. The interactions between electrons and acoustic phonon modes, the gauge field and deformation potential, are calculated at the DFT level in the framework of linear response. The zero-momentum limit of acoustic phonons is interpreted as a strain pattern, allowing the calculation of the acoustic gauge field parameter in the GW approximation. The role of electronic screening on the electron-phonon matrix elements is investigated. We then solve the Boltzmann equation semi-analytically in graphene, including both acoustic and optical phonon scattering. We show that, in the Bloch-Grüneisen and equipartition regimes, the electronic transport is mainly ruled by the unscreened acoustic gauge field, while the contribution due to the deformation potential is negligible and strongly screened. By comparing with experimental data, we show that the contribution of acoustic phonons to resistivity is doping- and substrate-independent. The DFT+GW approach underestimates this contribution to resistivity by about 30 %. Above 270K, the calculated resistivity underestimates the experimental one more severely, the underestimation being larger at lower doping. We show that, beside remote phonon scattering, a possible explanation for this disagreement is the electron-electron interaction that strongly renormalizes the coupling to intrinsic optical-phonon modes. Finally, after discussing the validity of the Matthiessen rule in graphene, we derive simplified analytical solutions of the Boltzmann equation to extract the coupling to acoustic phonons, related to the strain-induced gauge field, directly from experimental data.
Opposite impact of thermal expansion and phonon anharmonicity on the phonon-limited resistivity of elemental metals from first principles
European Theoretical Spectroscopy Facility, Institute of Condensed Matter and Nanosciences, Université catholique de Louvain（欧洲理论光谱设施，凝聚态物质与纳米科学研究所，天主教鲁汶大学）；Scientific Computing Department, Science and Technology Facilities Council, UK Research and Innovation, Daresbury Laboratory（科学与工程设施理事会英国研究与创新达尔斯伯里实验室科学计算部）；Département de Physique et Institut Courtois, Université de Montréal（蒙特利尔大学物理系与库瓦托瓦研究所）；Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science（魏茨曼科学研究所分子化学与材料科学系）；WEL Research Institute（WEL研究所）
Measurement of Elastoresistivity at Finite Frequency by Amplitude Demodulation
弹性电阻率，电阻率和应变之间的关系，可以阐明材料的电子结构的微妙性质，是研究强相关材料的一个越来越重要的工具。迄今为止，弹性电阻率测量主要是用准静态（DC）应变进行的。在这项工作中，我们演示了一种方法，使用AC应变的弹性电阻率测量。经历AC应变的样品具有随时间变化的电阻率，其调制由AC电流产生的电压;这种效应产生与弹性电阻率成正比的电阻率随时间变化，并且可以更快地测量，样品上的应变更小，并且对温度稳定性的要求比以前的DC技术更低。在10 Hz和3 kHz之间的示例测量在具有大的、良好表征的和温度依赖的弹性电阻率的材料上进行：代表性的铁基超导体BaFe $_{1.975}$ Co $_{0.025}$ As $_2$。这些测量产生一个频率无关的弹性电阻率和重现从以前的直流弹性电阻率方法的结果，在实验精度。我们强调，动态（AC）弹性电阻率是一个独特的材料特定的属性，以前没有被考虑。
Strain-Induced Metal-to-Insulator Transition in Antiferromagnetic SrCrO$_3$ Thin Films
University of Zurich（苏黎世大学）；ETH Zurich（苏黎世联邦理工学院）；Paul Scherrer Institut（保罗谢尔研究所）；Technical University of Vienna（维也纳工业大学）；PSI Center for Neutron and Muon Sciences（PSI中子与μ子科学中心）；Institut de Ciència de Materials de Barcelona (ICMAB-CSIC)（巴塞罗那材料科学研究所（ICMAB-CSIC））；ALBA Synchrotron Light Source（阿尔巴同步辐射光源）；Institut de Nanosciència i Nanotecnologia (ICN2)（纳米科学与纳米技术研究所（ICN2））；PSI Center for Photon Science（PSI光子科学中心）；University Paris Saclay（巴黎萨克雷大学）
An Environment-dependent Semi-Empirical Tight Binding Model Suitable for Electron Transport in Bulk Metals, Metal Alloys, Metallic Interfaces and Metallic Nanostructures II - Effect of Confinement and Homogeneous Strain on Cu Conductance
Effect of modulations of doping and strain on the electron transport in monolayer MoS_2
采用基于Boltzmann输运理论的第一性原理计算，系统研究了掺杂和应变对单层MoS_2电子输运的影响.我们估计在低掺杂水平下，在无应变条件下，迁移率有一个最大值275 cm ^2/（Vs）。施加小的应变（3%）可以将最大迁移率提高到1150 cm^2/（Vs），并且在高掺杂水平下应变效应更加显著。我们证明了电阻主要是由于M动量声子散射的K谷和Q谷之间的电子跃迁。然而，应变可以通过改变K谷和Q谷之间的能量差来有效地抑制这种类型的电子-声子耦合。这种迁移率对外部应变的敏感性可能指导MoS_2的电子输运的改善。
Strain control of mid-IR spectroscopic nonlinear photocurrents in PtSe$_2$
DEVCOM Army Research Laboratory（DEVCOM陆军研究实验室）；MIT Institute for Soldier Nanotechnologies（麻省理工学院士兵纳米技术研究所）；University of the Bundeswehr Munich（联邦国防军慕尼黑大学）
Epitaxial stabilization of pulsed laser deposited Sr$_{n+1}$Ir$_n$O$_{3n+1}$ thin films: entangled effect of growth dynamics and strain
Ir $^{4+}$层状氧化物中电子关联、晶场分裂和自旋-轨道耦合的微妙平衡可以产生新的电子和磁性相。这一领域的实验进展依赖于这些氧化物的外延膜的合成。然而，具有优异结构质量的层状虹彩晶体的生长是一个巨大的实验挑战。在这里，我们选择性地生长高质量的单相薄膜的Sr $_2$ IrO $_4$，Sr $_3$ Ir $_2$ O $_7$，和SrIrO $_3$在各种衬底上从一个单一的Sr $_3$ Ir $_2$ O $_7$目标通过调整背景氧压力和外延应变。我们证明了薄膜沉积过程中生长动力学和应变之间复杂的相互作用。这种相互作用导致在相同的生长条件下生长在不同衬底上的膜中的不同相的稳定，这不能用简单的动力学模型来解释。我们进一步研究了这三个阶段的热电性能，并提出，弱本地化是负责低温激活电阻率观察SrIrO $_3$压缩应变下。
