A5050740079- Ferroelectric and Piezoelectric Materials
- Multiferroics and related materials
- Electronic and Structural Properties of Oxides
- Magnetic and transport properties of perovskites and related materials
- Acoustic Wave Resonator Technologies
- Advanced Condensed Matter Physics
- Magnetic properties of thin films
- Semiconductor materials and devices
- Ferroelectric and Negative Capacitance Devices
- Microwave Dielectric Ceramics Synthesis
- Advanced Memory and Neural Computing
- Machine Learning in Materials Science
- 2D Materials and Applications
- Dielectric properties of ceramics
- Dielectric materials and actuators
- Characterization and Applications of Magnetic Nanoparticles
- Thermal properties of materials
- Advanced Sensor and Energy Harvesting Materials
- Magneto-Optical Properties and Applications
- Electron and X-Ray Spectroscopy Techniques
- Force Microscopy Techniques and Applications
- Advanced Thermoelectric Materials and Devices
- Solid-state spectroscopy and crystallography
- Advancements in Solid Oxide Fuel Cells
- Transition Metal Oxide Nanomaterials
University of California, Berkeley
2016-2025
Lawrence Berkeley National Laboratory
2016-2025
Rice University
2023-2025
University of California System
2018-2025
University of Minho
2023
Universidad de Cantabria
2023
Harbin Institute of Technology
2023
Montana State University
2022
Berkeley College
2018-2021
ORCID
2021
Piezoelectric materials, which convert mechanical to electrical energy and vice versa, are typically characterized by the intimate coexistence of two phases across a morphotropic phase boundary. Electrically switching one other yields large electromechanical coupling coefficients. Driven global environmental concerns, there is currently strong push discover practical lead-free piezoelectrics for device engineering. Using combination epitaxial growth techniques in conjunction with theoretical...
The authors report results of transport studies on high quality, fully epitaxial BiFeO3 thin films grown via pulsed laser deposition SrRuO3∕DyScO3 (110) substrates. Ferroelectric tests were conducted using symmetric and asymmetric device structures with either SrRuO3 or Pt top electrodes bottom electrodes. Comparison between these demonstrates the influence electrode selection dominant mechanism. Analysis film electrical response suggests Poole-Frenkel emission as limiting leakage current...
We report a photovoltaic effect in ferroelectric BiFeO3 thin films. The all-oxide heterostructures with SrRuO3 bottom and tin doped indium oxide top electrodes are characterized by open-circuit voltages ∼0.8–0.9 V external quantum efficiencies up to ∼10% when illuminated the appropriate light. Efficiencies at least an order of magnitude larger than maximum efficiency under sunlight (AM 1.5) thus far reported for ferroelectric-based devices. dependence measured voltage on film thickness...
The optical properties of epitaxial BiFeO3 thin films have been characterized in the visible range. Variable temperature spectra show an absorption onset near 2.17eV, a direct gap (2.667±0.005eV at 300K), and charge transfer excitations higher energy. Additionally, we report photoconductivity under illumination from 100mW∕cm2 white light source. A correlation is observed between magnitude postgrowth cooling pressure. Dark conductivities increased by order when comparing cooled 760 0.1Torr....
Out-of-plane ferroelectricity with a high transition temperature in ultrathin films is important for the exploration of new domain physics and scaling down memory devices. However, depolarizing electrostatic fields interfacial chemical bonds can destroy this long-range polar order at two-dimensional (2D) limit. Here we report experimental discovery locking between out-of-plane dipoles in-plane lattice asymmetry atomically thin In_{2}Se_{3} crystals, stabilization mechanism leading to our...
Multiferroic materials, or materials that simultaneously possess two more ferroic order parameters, have returned to the forefront of research. Driven by desire achieve new functionalities—such as electrical control ferromagnetism at room temperature—researchers undertaken a concerted effort identify and understand complexities multiferroic materials. The ability create high quality thin film multiferroics stands one single most important landmarks in this flurry research activity. In review...
Detailed analysis of transport, magnetism, and x-ray absorption spectroscopy measurements on ultrathin ${\text{La}}_{0.7}{\text{Sr}}_{0.3}{\text{MnO}}_{3}$ films with thicknesses from 3 to 70 unit cells resulted in the identification a lower critical thickness for nonmetallic nonferromagnetic layer at interface ${\text{SrTiO}}_{3}$ (001) substrate only three $(\ensuremath{\sim}12\text{ }\text{\AA{}})$. Furthermore, linear-dichroism demonstrate presence preferred...
We report the formation of a novel ferromagnetic state in antiferromagnet ${\mathrm{BiFeO}}_{3}$ at interface with ferromagnet ${\mathrm{La}}_{0.7}{\mathrm{Sr}}_{0.3}{\mathrm{MnO}}_{3}$. Using x-ray magnetic circular dichroism Mn and Fe ${L}_{2,3}$ edges, we discovered that development this spin structure is strongly associated onset significant exchange bias. Our results demonstrate directly related to an electronic orbital reconstruction interface, which supported by linearly polarized...
Advances in renewable and sustainable energy technologies critically depend on our ability to design realize materials with optimal properties. Materials discovery efforts ideally involve close coupling between prediction, synthesis characterization. The increased use of computational tools, the generation databases, advances experimental methods have substantially accelerated these activities. It is therefore an opportune time consider future prospects for by approaches. purpose this...
Defect-enhanced energy storage Dielectric capacitors are vital components of electronics and power systems. The thin-film materials which composed usually optimized by changing the material composition. However, Kim et al. found that postprocessing an already effective dielectric high-energy ion bombardment further improved because introduction specific types defects ultimately performance. results suggest may be important for developing next generation capacitors. Science , this issue p. 81
We demonstrate a direct correlation between the domain structure of multiferroic BiFeO3 thin films and exchange bias Co 0.9Fe 0.1/BiFeO3 heterostructures. Two distinct types interactions - an enhancement coercive field ( enhancement) combined with large shifts hysteresis loop bias) have been observed in these heterostructures, which depend directly on type crystallography nanoscale approximately 2 nm) walls film. show that magnitude interaction scales length 109 degrees ferroelectric BiFeO 3...
The control of material interfaces at the atomic level has led to novel interfacial properties and functionalities. In particular, study polar discontinuities between complex oxides lies frontier modern condensed matter research. Here we employ a combination experimental measurements theoretical calculations demonstrate bulk property, namely ferroelectric polarization, heteroepitaxial bilayer by precise atomic-scale interface engineering. More specifically, is achieved exploiting valence...