A5032053414- Multiferroics and related materials
- Ferroelectric and Piezoelectric Materials
- Magnetic and transport properties of perovskites and related materials
- Electronic and Structural Properties of Oxides
- Advanced Condensed Matter Physics
- Acoustic Wave Resonator Technologies
- Transition Metal Oxide Nanomaterials
- Advanced Memory and Neural Computing
- Magnetic Properties and Applications
- Force Microscopy Techniques and Applications
- ZnO doping and properties
- Magneto-Optical Properties and Applications
- Physics of Superconductivity and Magnetism
- 2D Materials and Applications
- Underwater Acoustics Research
- Dielectric properties of ceramics
- Magnetic properties of thin films
- Gas Sensing Nanomaterials and Sensors
- Magnetic Properties and Synthesis of Ferrites
- Solid-state spectroscopy and crystallography
- Graphene research and applications
- Perovskite Materials and Applications
- Electrochemical Analysis and Applications
- Semiconductor materials and devices
- MXene and MAX Phase Materials
Korea Advanced Institute of Science and Technology
2016-2025
Pohang University of Science and Technology
1999-2023
Oak Ridge National Laboratory
2023
Pusan National University
2017-2023
Ulsan National Institute of Science and Technology
2023
Kootenay Association for Science & Technology
2023
Kongju National University
2018
UNSW Sydney
2017
Materials Science & Engineering
2017
Korea Institute of Materials Science
2017
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...
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...
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...
The transport physics of domain wall conductivity in La-doped bismuth ferrite (BiFeO3) has been probed using variable temperature conducting atomic force microscopy and piezoresponse samples with arrays walls the as-grown state. Nanoscale current measurements are investigated as a function bias shown to be consistent distinct electronic properties at leading changes observed local conductivity. Our observation is well described within band picture conduction. Finally, we demonstrate an...
BiFeO3 is one of the most studied multiferroic materials. Both its magnetic and ferroelectric properties can be influenced by doping. A large body work on doped material has been presented in past couple years. In this paper we provide a perspective general doping concepts their impact material's functionality.
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...
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...
Abstract Transition metal oxides (TMOs) are an important class of materials that show a wide range functionalities involving spin, charge, and lattice degrees freedom. The strong correlation between electrons in d -orbitals the multivalence nature give rise to variety exotic electronic states ranging from insulator superconductor cause intriguing phase competition phenomena. Despite burst research on multifarious TMOs, little attention has been paid formation integration electret—a type...
Successful synthesis of room-temperature ferromagnetic semiconductors, Zn$_{1-x}$Fe$_{x}$O, is reported. The essential ingredient in achieving ferromagnetism bulk Zn$_{1-x}$Fe$_{x}$O was found to be additional Cu doping. A transition temperature as high 550 K obtained Zn$_{0.94}$Fe$_{0.05}$Cu$_{0.01}$O; the saturation magnetization at room reached a value $0.75 \mu_{\rm B}$ per Fe. Large magnetoresistance also observed below $100 $K.
Control over ferroelectric polarization variants in BiFeO3 films through the use of various vicinal SrTiO3 substrates is demonstrated. The revolution domain formation as a function vicinality characterized, and these corresponding structural are carefully analyzed. piezo/ferroelectric properties films, turn, can be tailored this approach.
We demonstrate an approach to create a one-dimensional nanoscale array of domain walls in epitaxial La-substituted BiFeO(3) films. have used DyScO(3) (110)(O) single-crystal substrate provide anisotropic strain exclude two the possible structural variants. Furthermore, through careful control electrostatic boundary conditions, such as thickness SrRuO(3) bottom electrode induce self-poling effects, we can choose obtain either 109 degrees or 71 periodic walls. Detailed measurements structures...
Ferroelectric size effects in multiferroic BiFeO3 have been studied using a host of complementary measurements. The structure such epitaxial films has investigated atomic force microscopy, transmission electron and x-ray diffraction. crystal the identified as monoclinic phase, which suggests that polarization direction is close to ⟨111⟩. Such behavior also confirmed by piezoforce microscopy That reveals ferroelectricity down at least 2nm.
We have studied the surface termination of atomically flat SrTiO3 surfaces treated by chemical etching and subsequent thermal annealing, for all commercially available orientations (001), (110), (111). Atomic force microscopy confirms that our treatment processes produce unit cell steps with terrace structures. also determined topmost atomic layer through time-of-flight mass spectroscopy. found three exhibit a Ti-rich surface. Our observation opens doors interface engineering along [110]...
A planar slab of negative-index material works as a superlens with sub-diffraction-limited resolution, propagating waves are focused and, moreover, evanescent reconstructed in the image plane. Here we demonstrate for electric fields low losses using perovskites mid-infrared regime. The combination near-field microscopy tunable free-electron laser allows us to address precisely polariton modes, which critical super-resolution imaging. We spectrally study lateral and vertical distributions...
Topological defects in matter behave collectively to form highly non-trivial structures called topological textures that are characterised by conserved quantities such as the winding number. Here we show an epitaxial ferroelectric square nanoplate of bismuth ferrite subjected a large strain gradient (as much 105 m-1) associated with misfit relaxation enables five discrete levels for invariant entire system because its peculiar radial quadrant domain texture and inherent wall chirality. The...
We have probed the role of La substitution on ferroelectric properties epitaxial BiFeO3 films SrTiO3-templated Si. This provides a mechanism to engineer rhombohedral distortion in crystal and, thus, control domain structure and switching. With 10% substitution, (Bi0.9La0.1)FeO3 film showed well-saturated hysteresis loops with remanent polarization 45μC∕cm2, converse piezoelectric coefficient d33 45pm∕V, dielectric constant 140. Over this range coercive field systematically decreases such...
The ultimate challenge for the development of new multiferroics with enhanced properties lies in achieving nanoscale control coupling between different ordering parameters. In oxide-based multiferroics, substitutional cation dopants offer unparalleled possibility to modify both electric and magnetic at a local scale. Herein it is demonstrated formation dopant-controlled polar pattern BiFeO3 leading spontaneous instauration periodic polarization waves. particular, nonpolar Ca-doped rich...