Mesoscale Phenomena in Functional Polycrystals and Their Nanostructures: Dielectric and Magnetic Phenomena
Sponsored by: ACerS Electronics Division
Program Organizers: Serge Nakhmanson, University of Connecticut; Edward Gorzkowski, Naval Research Laboratory; James Wollmershauser, U.S. Naval Research Laboratory; Seungbum Hong, KAIST; Javier Garay, University of California, San Diego; Pierre-Eymeric Janolin, CentraleSupélec
Wednesday 2:00 PM
October 12, 2022
Room: 412
Location: David L. Lawrence Convention Center
Session Chair: Seungbum Hong, KAIST; John Mangeri, LIST; James Wollmershauser, NRL
2:00 PM Invited
Strain-induced Novel Quantum and Ionic Phenomena in Oxide Heterostructures: Honyung Lee1; 1Oak Ridge National Laboratory
Complex oxides are known to possess a full spectrum of fascinating properties, including magnetism, superconductivity, (multi)ferroicity, and ionic conductivity, to name a few. Spurred by recent advances in the synthesis of thin films and nanomaterials of complex oxides, the atomic- and meso-scale growth control enables to assemble the building blocks to a functional system in programmable manner, yielding many intriguing physical properties that cannot be found in bulk counterparts. In this talk, examples of functional complex oxides will be presented to highlight atomic- and meso-scale assembly of complex oxides with a particular focus on the use of epitaxial strain to create novel functional properties in oxide heterostructures. The main topics include (1) autonomous control of oxygen defect and cationic distribution by strain, and (2) strain-induced formation of oxide Dirac semimetal in strained SrNbO3 that enters the extreme quantum limit, and (3) non-equilibrium synthesis of oxide nanobrush architectures for ionic applications.
2:30 PM Invited
Optimization of Metal/Ferroelectric/Insulator/Semiconductor Capacitor Toward Reliable Gate Stacks of Field-effect-transistors: Min Hyuk Park1; Younghwan Lee1; 1Seoul National University
Ferroelectricity in hafnia-based ferroelectrics has attracted increasing interest since 2011, and ferroelectric field-effect-transistors (FeFETs) are considered promising for future computing paradigms. The core part of FeFETs is the metal/ferroelectric/insulator/semiconductor (MFIS) stack, and it is considered as the origin of the limited endurance and retention of FeFETs with hafnia-based ferroelectric. The problematic part of MFIS stack was suggested as the ferroelectric/semiconductor interfaces with high trap site concentration. The charge trapping in the gate oxide as well as the interfacial trap generation were the main cause of device failure. In this presentation, the interfacial engineering strategies to improve the reliability of the FeFET gate stack are presented based on our recent experimental results from MFIS capacitors.[1] Reference[1] S. H. Kim et al. Chem. Commun. 57 (93), 12452-12455 (2021)
3:00 PM
Modeling the Relaxor Dielectric Dispersion of Ba(1−x)Sr(x)TiO3 with a Local Phase Field Method: Ashok Gurung1; John Mangeri2; S. Pamir Alpay1; Serge Nakhmanson1; 1University of Connecticut; 2Luxembourg Institute of Science and Technology
The solid solution Ba(1−x)Sr(x)TiO3 (BST) displays a highly tunable dielectric response, while exhibiting low losses in a broad frequency regime, including microwave. There is a need for better understanding of the influence of BST microstructure on its properties and performance. Since local polarization in BST is strongly dependent on composition, so is its response to an applied AC field. Here, we have adopted a phase field method to study the frequency dependent dielectric response of BST, while accounting for the local composition fluctuations. We connected relaxor-like features in the dielectric dispersion to local spatial inhomogeneities, such as average size of Ba-rich regions, across a wide range of temperatures. These results show that the simple coarse-grained approach to the relaxor problem is sensitive enough to reveal correlations between the frequency dependence of the dielectric response and modulations in the material morphology and microstructure.
3:20 PM Invited
Coupled Multiferroic Phase Field Models for BiFeO3: Domain Topologies and Order Parameter Dynamics: John Mangeri1; 1Luxembourg Institute of Science and Technology
BiFeO3 has garnered significant interest because of its remarkable room temperature multiferroic properties. It has been proposed as an integral component of magnetoelectric spin-orbit logic devices which would form the backbone of next-generation information processing. Leveraging the open-source finite element framework MOOSE, we have developed a continuum-based approach that couples the Landau-Ginzburg theory of the ferroelectric phase transition along with the Landau-Lifshitz-Gilbert equation which governs micromagnetism. The model parameters are all derived from first-principles calculations whether directly or indirectly. This developed coarse-grained method is capable of simulating both the magnetic spins and the structural distortions in a single simulation on length and time scales not accessible to atomistic approaches. I will present results of electric-field driven switching of the polar and antiferromagnetic order parameters along with calculations of spin-wave transport across different domain wall topologies.**Funding from the European Union's research programme (H2020-EU.1.3.2.) under Marie Sklodowska-Curie grant agreement SCALES-897614
3:50 PM Break
4:10 PM
Mesoscale Magnetic Imaging of Functional Materials: Ilya Sochnikov1; Bochao Xu1; Joshua Bedard1; Jacob Franklin1; 1University of Connecticut
Magnetic properties are important in various materials with applications ranging from magnetic memory to structural alloys. In most cases, the magnetization measurements are done on bulk samples that is ‘bulk measurements’. However, knowing the mesoscopic distribution of properties could be crucial as they can be very different from bulk properties. Here, I will introduce our magnetic imaging technique utilizing superconducting nanoscale sensors. I will showcase several studies from our laboratory and other works. Examples of the studied mesoscale objects and effects include domains, crystalline grains, composite nanoparticles, magnetostriction, edge magnetization, magnetization at dislocations, magnetization change from interdiffusion etc. I will summarize my talk by outlining prospective studies of relation between magnetic and other properties for improving the overall material performance.
4:30 PM Invited
Field-assisted Sintering of FeCo/MnZn Ferrite Core-Shell Structured Particles: Bowen Dong1; Haobo Wang1; Matthew Willard1; Gabriel Santillan2; Andrew Sherman2; 1Case Western Reserve University; 2Powdermet
Core-shell FeCo/MnZn ferrite powders were prepared by the sol-gel method with target composition for the MnZn ferrite shell of Mn0.8Zn0.2Fe2O4. The powders were compacted into bulk composites with FeCo separated by an oxide matrix using the field-assisted sintering technique (FAST) at 800°C for 10 min. All resulting compacts achieved relative density >95%. As the MnZn ferrite content in the original core-shell powder increases from 5.01 to 17.10 wt.%, the saturation magnetization of the compacts decreases from 222 Am2/kg to 165 Am2/kg, and the coercivity increases from 772 A/m to 1654 A/m. XRD of the compacts indicates that a chemical reaction dissociates the spinel-structured MnZn ferrite into a rocksalt structured phase. Thermodynamics calculation indicates that the reaction happens between FeCo and MnZn ferrite at 800°C, but favors MnZn ferrite at temperatures 400°C. This prediction was substantiated by FAST consolidation at 400°C. (Supported by NASA SBIR under Contract Number 80NSSC19C0358)
4:50 PM Invited
Supercrystals as Hybrid Nanostructured Materials with Tailored Mechanical and Magnetic Properties: Diletta Giuntini1; 1Hamburg University of Technology
Nano/micro-structured ceramics combine the unique features of ultra-small building blocks and their organization into long-range order patterns to foster new properties up to the macroscale. Many functional applications open up, in catalysis, energy, optoelectronics, and more. Supercrystalline nanocomposites are a promising example, consisting of inorganic nanoparticles interfaced by an ultra-thin organic phase. This talk tackles multiple aspects of these new hybrid materials: from fundamental studies of their nanostructural analogies with atomic crystals and the occurrence of superlattice defects, all the way to potential applications via tailored magnetic properties. Strategies to enhance their mechanical behavior will also be laid out, as inferred through ex and in situ studies in multiple loading conditions.