Computational Thermodynamics and Kinetics: Electrons and Phonons
Sponsored by: TMS Functional Materials Division, TMS Materials Processing and Manufacturing Division, TMS: Chemistry and Physics of Materials Committee, TMS: Computational Materials Science and Engineering Committee, TMS: Integrated Computational Materials Engineering Committee, TMS: Solidification Committee
Program Organizers: Hesam Askari, University Of Rochester; Damien Tourret, IMDEA Materials Institute; Eva Zarkadoula, Oak Ridge National Laboratory; Enrique Martinez Saez, Clemson University; Frederic Soisson, Cea Saclay; Fadi Abdeljawad, Lehigh University; Ziyong Hou, Chongqing University
Thursday 2:00 PM
March 23, 2023
Room: 26A
Location: SDCC
Session Chair: Zhenglu Li, University Of Southern California; Damien Tourret, IMDEA Materials Institute
2:00 PM Invited
Correlation-enhanced Electron-phonon Coupling in Oxide Superconductors from Ab Initio GW Perturbation Theory: Zhenglu Li1; 1Lawrence Berkeley National Lab/UC Berkeley/University of Southern California
Quantum materials host exotic electronic phases and are central for future energy, device, and materials engineering. A grand challenge in computational materials science is to accurately describe quantum excitations associated with complex interactions. This talk will discuss some exciting new progress in the first-principles computation of materials’ excited states within the framework of many-body perturbation theory (e.g., the GW method and beyond). Recently, we have achieved for the first time the accurate, many-electron-level computation of electron-phonon coupling by developing the GW perturbation theory (GWPT), going beyond the standard density functional theory which is inadequate to capture correlation effects in many cases. I will showcase that using GWPT, how we resolved some long-standing puzzles in oxide superconductors (32-K superconductivity in Ba1-xKxBiO3 and photoemission kink in the cuprates) by revealing an unexpected and significant correlation-enhanced electron-phonon coupling.
2:30 PM Cancelled
A Finite-element Phase-field Model of Topological Defect Formation in Epitaxially Grown Ferroelectric Thin Films: Soumya Bandyopadhyay1; Ranjith Ramadurai2; Saswata Bhattacharyya2; 1School of Advanced Materials Engineering, Kookmin University; 2Indian Institute of Technology Hyderabad
Complex interplay of electrostatic dipole-dipole interactions, ferroelastic interactions and electro-elastic coupling govern domain evolution in ferroelectric thin films. Therefore, domain pattern formation is highly sensitive to electrical and mechanical boundary conditions. Although phase-field method has been widely employed to study domain evolution in ferroelectric films and superlattices, most numerical implementations using finite difference or Fourier spectral methods consider regular geometries with simple boundary conditions. On the other hand, finite element implementation can handle complex geometries as well as intricate boundary conditions. Here, we show such an implementation in two and three dimensions using MOOSE - an open-source finite element framework. Our simulations can accurately capture the sensitivity of solutions to changes in electromechanical boundary conditions. We show that open-circuit boundary conditions for certain thicknesses of free-standing as well as epitaxially strained films lead to stabilization of topological defect states such as polar vortices, flux closure domains and polar skyrmions.
2:50 PM
An Electrochemical Repertoire for Triggering Phase Transitions in Insulators: The Case of Monoclinic/Tetragonal Transition in ZrO2: Mostafa Youssef1; 1The American University in Cairo
Phase transitions can be either degrading or desirable. An important transition that is cited to be both degrading and desirable is the monoclinic/tetragonal phase transition in ZrO2. Although it has been mainly discussed as stress-driven, in this work we show that it can also be driven by lattice defects. The free energy of both phases were computed accounting for the contribution of lattice defects under the action of three thermodynamic forces; oxygen chemical potential, impurity chemical potential such as hydrogen, and external electric bias. The results were cast in phase diagrams. Poor oxygen conditions and/or negative electric bias can stabilize tetragonal ZrO2 below its commonly cited stabilization temperature. Meanwhile, hydrogen impurity can reverse the effect and re-stabilize the monoclinic phase. Thus, we provide new insights to the origins of stabilizing the tetragonal phase in oxidized zirconium alloys and new explanations to the mechanism of the water-induced degradation of ZrO2 ceramics.
3:10 PM
Controlling the Stability and Reliability Issues of the Electrical Responses of Resistive RAM and Neuromorphic Computing Devices: A Phase Field Study: Arijit Roy1; Min-Gyu Cho1; Hwi-Jae Cho1; Pil-Ryung Cha1; 1Kookmin University
Organic and inorganic semiconducting systems are continuously being investigated to improve the performance of resistive RandomAccessMemory (ReRAM) and neuromorphic computing devices. Developing the new generation of memristor devices is challenging due to the involvement of various materials and processing issues. Application of electric field triggers the formation of conducting filament (CF) in memristive systems. We use phase field model to study morphological evolution of CF. We successfully simulate the voltage sweeping cycle mediated formation and breaking of CF leading to SET and RESET processes. We could also model voltage pulse mediated growth of CF, crucial for memory and learning experience behaviors in neuromorphic computation. We further validate our numerical results with experimental observations available in the literature. We believe such correlations of operation conditions with electrical responses -- responsible for device failure during endurance cycles and learning behavior during voltage pulsing cycles -- could shape the future of memristor research.
3:30 PM Break
3:50 PM
A High-Throughput Framework for Lattice Dynamics: Zhuoying Zhu1; Junsoo Park1; Anubhav Jain1; 1LBNL
Lattice dynamics of materials are fundamental to their thermal properties, mechanical properties, as well phase transition behaviors. Among thermodynamic quantities that directly follow from harmonic phonons are vibrational free energy, entropy, and heat capacity, which can be easily obtained from well-known methods like density-functional perturbation theory. Obtaining anharmonic IFCs (third-order and higher), which determine thermal expansion, thermal conductivity, and dynamical stability has remained a challenge for longer.We herein present our generalized automated workflow for lattice dynamical properties. Under the high-throughput framework, we can obtain both harmonic and anharmonic IFCs with HiPhive package and calculate quantities like three-phonon scattering and lattice thermal conductivity using ShengBTE. For phonon dispersions with imaginary modes, one more step of renormalization will be added to obtain temperature-dependent real and stable phonons before computing the thermodynamic quantities.
4:10 PM
Strain Engineering of Ferroelectric Domains in Epitaxially Grown Barium Zirconate Titanate – Barium Calcium Titanate (BZT-xBCT) Films near Morphotropic Phase Boundary Composition: Phase-field Simulations and Experimental Realization: Vaishnavi S M1; Soumya Bandyopadhyay2; Sabarigresan Murugan1; Saswata Bhattacharya1; Ranjith Ramadurai1; 1Indian Institute of Technology, Hyderabad; 2School of Advanced Materials Engineering, Kookmin University
Tuning epitaxial misfit strain is an effective strategy to tailor ferroelectric properties of epitaxially grown films. Since bulk BZT-xBCT solid solution exhibit enhanced ferroelectric and piezoelectric properties at room temperature at the morphotropic phase boundary (MPB), with a view to strain-tuning the electromechanical response of this lead-free ferroelectric system, we investigate the role of epitaxial misfit on ferroelectric domain evolution in BZT-xBCT films near the MPB composition using a combination of phase-field simulations and piezo-response force microscopy experiments. The change in biaxial strain from compressive (Ɛ=-0.01) to tensile (Ɛ =+0.01) leads to significant change in the simulated domain structure from tetragonal fractal-like domains to orthorhombic checker-board like domain pattern. To realize such changes in domain evolution, epitaxial films of the same thickness were grown by pulsed laser ablation maintaining similar strain conditions and Piezo-response force microscopy of these films reveal very similar patterns as predicted by the phase-field simulations.
4:30 PM
Examining the Alpha-epsilon Transition in Iron Using Molecular-spin Dynamics: Svetoslav Nikolov1; Andrew Rohskopf1; Julien Tranchida2; Kushal Ramakrishna3; Attila Cangi3; Mitchell Wood1; 1Sandia National Laboratories; 2CEA; 3CASUS
For magnetic materials, like iron, that exhibit strong spin-orbit coupling, resolving the magnetic degrees of freedom is critical for understanding the corresponding thermal and mechanical responses. In the current effort, we utilize a machine-learned framework to train a SNAP interactomic potential and biquadratic spin exchange Hamiltonian on first principles high temperature/pressure data. The trained multi-potential model is then applied in a molecular-spin dynamics simulations, where we examine how the phonon density of states and thermal conductivities vary throughout the alpha-epsilon transition of iron. The spin dynamics model is modified to enable longitudinal spin fluctuations, whose impact on the alpha-epsilon transition is assessed.
4:50 PM
High Pressure Phonon Thermodynamics of B2-ordered Equiatomic Iron-vanadium (FeV): Homero Reyes1; Ravhi Kumar2; Bimal K C1; Russell Hemley2; Jorge Munoz1; 1University of Texas at El Paso; 2University of Illinois Chicago
The iron-vanadium system has been studied extensively because of its rich magnetism and order-disorder phase transitions. We will present results obtained with density functional theory (DFT) for FeV at high pressure and for several temperatures. At 0K, the cubic structure becomes unstable at 30 GPa with respect to the atomic displacements of the transverse acoustic (TA) M5 phonon modes. The TA M5 phonon modes behave anomalously, softening with pressure and stiffening with temperature. We attribute the former to a charge build-up between 2NN vanadium atoms that preferentially screen certain ionic motions. This effect is delicate and is significantly weakened by thermal atomic disorder, explaining the latter. We obtained x-ray diffraction patterns in a diamond-anvil cell at 300K and up to 80 GPa and did not observe a phase transition, potentially indicating that the transition occurs at a lower temperature.
5:10 PM
Thermodynamic and Kinetic Temperature-electric Field Diagrams for Ferroelectric HfO2 Based on Atomistic Simulation: Sahar Abdelazim1; Mostafa Youssef1; 1The American University in Cairo
Since the discovery of ferroelectricity in hafnia (HfO2), interest in this material has increased in many applications particularly in electronics devices including ferroelectric random-access memories. This is due to its preserved unique ferroelectricity till few nanometers. This unique ferroelectricity of hafnia being a binary oxide is believed to be stabilized by several thermodynamic factors among which oxygen vacancies are key ones. Herein we employ classical molecular dynamics to uncover unique structural and kinetic properties for oxygen vacancies in HfO2 as a function of temperature (T) and electric field (E). The results are depicted on T-E diagrams and transitions are explained based on atomistic details and polarization changes. Our work provides insights into the performance of ferroelectric HfO2 in its applications.