A5101750525- Electronic and Structural Properties of Oxides
- Ferroelectric and Piezoelectric Materials
- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- Multiferroics and related materials
- Physics of Superconductivity and Magnetism
- Semiconductor materials and devices
- Acoustic Wave Resonator Technologies
- Ferroelectric and Negative Capacitance Devices
- Advanced Memory and Neural Computing
- Perovskite Materials and Applications
- Nanowire Synthesis and Applications
- Photonic Crystals and Applications
- Surface Roughness and Optical Measurements
- Electrowetting and Microfluidic Technologies
- Gas Sensing Nanomaterials and Sensors
- Graphene research and applications
- ZnO doping and properties
- Force Microscopy Techniques and Applications
- 2D Materials and Applications
- Topological Materials and Phenomena
Yale University
2019-2025
Seoul National University
2012-2021
Interface (United States)
2021
University of New Haven
2021
Paul Scherrer Institute
2021
Rutgers, The State University of New Jersey
2021
Institute for Basic Science
2014-2020
Hankuk University of Foreign Studies
2017
Seoul National University of Education
2017
Ferroelectric tunnel junctions (FTJs) have attracted increasing research interest as a promising candidate for nonvolatile memories. Recently, significant enhancements of tunneling electroresistance (TER) been realized through modifications electrode materials. However, direct control the FTJ performance modifying barrier has not adequately explored. Here, adding new direction to research, we fabricated FTJs with BaTiO3 single barriers (SB-FTJs) and BaTiO3/SrTiO3 composite (CB-FTJs) reported...
Flexoelectric control of defect formation and associated electronic function is demonstrated in ferroelectric BiFeO3 thin films. An intriguing, so far never demonstrated, effect internal electric field (Eint) on explored by a means flexoelectricity. Our study provides novel insight into engineering, as well allows pathway to design configuration function.
Active control of defect structures and associated polarization switching in a ferroelectric material is achieved without compromising its properties. Based on dipolar interaction between dipole polarization, the unique functionality to visualized. This approach can provide foundation for novel applications, such as high-density multilevel data storage. Detailed facts importance specialist readers are published "Supporting Information". Such documents peer-reviewed, but not copy-edited or...
Abstract Oxygen vacancies, especially their distribution, are directly coupled to the electromagnetic properties of oxides and related emergent functionalities that have implications for device applications. Here using a homoepitaxial strontium titanate thin film, we demonstrate controlled manipulation oxygen vacancy distribution mechanical force from scanning probe microscope tip. By combining Kelvin microscopy imaging phase-field simulations, show vacancies can move under...
The atomic‐scale synthesis of artificial oxide heterostructures offers new opportunities to create novel states that do not occur in nature. main challenge related synthesizing these structures is obtaining atomically sharp interfaces with designed termination sequences. In this study, it demonstrated the oxygen pressure during growth plays an important role controlling interfacial terminations SrRuO 3 /BaTiO /SrRuO (SRO/BTO/SRO) ferroelectric (FE) capacitors. SRO/BTO/SRO are grown by a...
Efforts have been ongoing to establish superconducting spintronics utilizing ferromagnet/superconductor heterostructures1. Previously reported devices are based on spin-singlet superconductors (SSCs), where the spin degree of freedom is lost. Spin-polarized supercurrent induction in ferromagnetic metals (FMs) achieved even with SSCs, but only aid interfacial complex magnetic structures, which severely affect information imprinted electron spin. Use spin-triplet (TSCs) active spins...
Ferroelectric interfacial devices consist of materials systems whose electronic properties (such as a 2D electron gas or an magnetic spin configuration) are modulated by ferroelectric layer set in its immediate vicinity. While the prototypical example such system is field effect transistor first proposed 1950s, only with recent advances controlled growth epitaxial thin films and heterostructures, physical understanding down to atomic scale screening processes at ferroelectric-semiconducting...
Ferromagnetic SrRuO3 thin films are deposited on the ab surface of single crystals spin-triplet superconductor (TSC) Sr2RuO4 as substrates using pulsed laser deposition. The under a severe in-plane compressive strain. Nevertheless, exhibit ferromagnetic order with easy axis along c-direction below Curie temperature 158 K. electrical transport reveals that SrRuO3/Sr2RuO4 interface is highly conducting, in contrast between other normal metals and Sr2RuO4. Our results stimulate investigations...
With recent trends on miniaturizing oxide-based devices, the need for atomic-scale control of surface/interface structures by pulsed laser deposition (PLD) has increased. In particular, realizing uniform atomic termination at is highly desirable. However, a lack understanding surface formation mechanism in PLD limited deliberate stacking sequences. Here, taking prototypical SrRuO3/BaTiO3/SrRuO3 (SRO/BTO/SRO) heterostructure as model system, we investigated different interfacial sequences...
Abstract Switching dynamics of ferroelectric materials are governed by the response domain walls to applied electric field. In epitaxial films, thermally-activated ‘creep’ motion plays a significant role in wall and accordingly, detailed understanding system’s switching properties requires that this creep be taken into account. Despite importance, few studies have investigated films under ac -driven force. Here, we explore hysteretic BiFeO 3 thin through hysteresis measurements stroboscopic...
BaTiO3 exhibits several functional properties, such as high dielectric constant, large Pockels coefficient, and strong ferroelectricity/piezoelectricity. These properties can be used for a variety of applications, ferroelectric tunnel junctions in non-volatile memory devices. To achieve large-scale integration BaTiO3, however, one requires the synthesis high-quality films at low temperatures order to compatible with thermal budget electronic processes use today. Here, we describe thin by...
We report magnetic properties of epitaxial thin films the itinerant ferromagnet SrRuO3 deposited on cleaved ab surface spin-triplet superconductor Sr2RuO4. The exhibit ferromagnetic transition near 160 K as in bulk SrRuO3, although are under 1.7% compressive strain. observed magnetization is even higher than that SrRuO3. In addition, we newly found relaxation after field removal strongly anisotropic: two processes involved when domains aligned along ab-plane.
Abstract ABO 3 perovskite materials and their derivatives have inherent structural flexibility due to the corner sharing network of BO 6 octahedron, large variety possible distortions strong coupling between lattice charge/spin degrees freedom led emergence intriguing properties, such as high‐temperature superconductivity, colossal magnetoresistance, improper ferroelectricity. Here, an unprecedented polar ferromagnetic metal phase in SrRuO (SRO) thin films is presented, arising from...
We report the effect of an internal field on high resistance state (HRS) retention unipolar switching in ferroelectric vanadium (V) doped ZnO thin films. films with 1%, 3%, and 5% V were found to have increased as concentration increased. The was observed from lower set voltage shorter time. A physical model applied explain relationship between HRS retention, a good agreement obtained experimental data. Our result suggested that can reduce activation energy redox process for generating...
We report on a surface-induced, insulating, electrically dead layer in ultrathin conducting La-doped SrTiO3 thin films. Systematic studies electrical properties as function of film thickness and La-doping levels reveal that the insulating has constant traps amount electron density regardless levels. Growing an additional capping top surface counteracts reduced conductivity, indicating strong relationship between structure. Our results emphasize importance state for functional oxides limit...
Abstract Quantum mechanical tunneling of electrons across ultrathin insulating oxide barriers has been studied extensively for decades due to its great potential in electronic‐device applications. In the few‐nanometers‐thick epitaxial films, atomic‐scale structural imperfections, such as ubiquitously existed one‐unit‐cell‐high terrace edges, can dramatically affect probability and device performance. However, underlying physics not investigated adequately. Here, taking BaTiO 3 films a model...
Oxide single-crystal substrates with atomically smooth and chemically uniform surfaces are indispensable for constructing high-quality epitaxial heterostructures sharp heterointerfaces. In this paper, the authors develop a simple efficient recipe to optimize surface structure in LaAlO${}_{3}$ (001) single crystal, widely used substrate growing perovskite oxide heterostructures. The combine thermal annealing subsequent deionized water leaching processes treat surface. Thanks distinct...
The atomic-scale synthesis of artificial oxide heterostructures offers new opportunities to create novel states that do not occur in nature. main challenge related synthesizing these structures is obtaining atomically sharp interfaces with designed termination sequences. Here, we demonstrate the oxygen pressure (PO2) during growth plays an important role controlling interfacial terminations SrRuO3/BaTiO3/SrRuO3 (SRO/BTO/SRO) ferroelectric capacitors. SRO/BTO/SRO were grown by pulsed laser...
Abstract In research on functional materials, the focus of attention has increasingly shifted from ferroelectrics, with electric‐field‐driven switching between two or more symmetry‐related insulating polar states, to materials behavior based competition antipolar and symmetry inequivalent driven by applied electric fields and/or stresses. When competing states are not related, they can have quite distinct magnetic, optical, transport, topological properties, functionality derived modulating...