Feld-induced modulation of two-dimensional electron gas at LaAlO/SrTiO interface by polar distortion of LaAlO.

Since the discovery of two-dimensional electron gas at the LaAlO/SrTiO interface, its intriguing physical properties have garnered significant interests for device applications. Yet, understanding its response to electrical stimuli remains incomplete. Our in-situ transmission electron microscopy analysis of a LaAlO/SrTiO two-dimensional electron gas device under electrical bias reveals key insights.

Deterministic Orientation Control of Ferroelectric HfO Thin Film Growth by a Topotactic Phase Transition of an Oxide Electrode.

The scale-free ferroelectricity with superior Si compatibility of HfO has reawakened the feasibility of scaled-down nonvolatile devices and beyond the complementary metal-oxide-semiconductor (CMOS) architecture based on ferroelectric materials. However, despite the rapid development, fundamental understanding, and control of the metastable ferroelectric phase in terms of oxygen ion movement of HfO remain ambiguous. In this study, we have deterministically controlled the orientation of a single-crystalline ferroelectric phase HfO thin film via oxygen ion movement.

Surface triggered stabilization of metastable charge-ordered phase in SrTiO.

Charge ordering (CO), characterized by a periodic modulation of electron density and lattice distortion, has been a fundamental topic in condensed matter physics, serving as a potential platform for inducing novel functional properties. The charge-ordered phase is known to occur in a doped system with high d-electron occupancy, rather than low occupancy. Here, we report the realization of the charge-ordered phase in electron-doped (100) SrTiO epitaxial thin films that have the lowest d-electron occupancy i.

Enhanced ferroelectric switching speed of Si-doped HfO thin film tailored by oxygen deficiency.

Investigations concerning oxygen deficiency will increase our understanding of those factors that govern the overall material properties. Various studies have examined the relationship between oxygen deficiency and the phase transformation from a nonpolar phase to a polar phase in HfO thin films. However, there are few reports on the effects of oxygen deficiencies on the switching dynamics of the ferroelectric phase itself.

Complementary Resistive Switching and Synaptic-Like Memory Behavior in an Epitaxial SrFeO Thin Film through Oriented Oxygen-Vacancy Channels.

Oxygen-vacancy-ordered brownmillerite oxides offer a reversible topotactic phase transition by significantly varying the oxygen stoichiometry of the material without losing its lattice framework. This phase transition leads to substantial changes in the physical and chemical properties of brownmillerite oxides, including electrical and ion conductivity, magnetic state, and oxygen diffusivity. In this study, the variations in the resistive switching mode of the epitaxial brownmillerite SrFeO thin film in the device were studied by systematically controlling the oxygen concentration, which could be varied by changing the compliance current during the first electroforming step.

Scale-free ferroelectricity induced by flat phonon bands in HfO.

Discovery of robust yet reversibly switchable electric dipoles at reduced dimensions is critical to the advancement of nanoelectronics devices. Energy bands flat in momentum space generate robust localized states that are activated independently of each other. We determined that flat bands exist and induce robust yet independently switchable dipoles that exhibit a distinct ferroelectricity in hafnium dioxide (HfO).

Stable Subloop Behavior in Ferroelectric Si-Doped HfO.

The recent demand for analogue devices for neuromorphic applications requires modulation of multiple nonvolatile states. Ferroelectricity with multiple polarization states enables neuromorphic applications with various architectures. However, deterministic control of ferroelectric polarization states with conventional ferroelectric materials has been met with accessibility issues.

A Room-Temperature Ferroelectric Ferromagnet in a 1D Tetrahedral Chain Network.

Ferroelectricity occurs in crystals with broken spatial inversion symmetry. In conventional perovskite oxides, concerted ionic displacements within a 3D network of transition-metal-oxygen polyhedra (MO ) manifest spontaneous polarization. Meanwhile, some 2D networks of MO foster geometric ferroelectricity with magnetism, owing to the distortion of the polyhedra.

Ferroelectric Polarization-Switching Dynamics and Wake-Up Effect in Si-Doped HfO.

The ferroelectricity in ultrathin HfO offers a viable alternative to ferroelectric memory. A reliable switching behavior is required for commercial applications; however, many intriguing features of this material have not been resolved. Herein, we report an increase in the remnant polarization after electric field cycling, known as the "wake-up" effect, in terms of the change in the polarization-switching dynamics of a Si-doped HfO thin film.

In-line ultrasonic monitoring for sediments stuck on inner wall of a polyvinyl chloride pipe.

This research verified the applicability and effectiveness of the ultrasonic monitoring of sediments stuck on the inner wall of polyvinyl chloride (PVC) pipes. For identifying the transmittance of acoustic energy and the speed of sound in the PVC material, the pulse-echo ultrasonic testing was conducted for PVC sheets of different thicknesses. To simulate the solidified sediment, the hot melt adhesive (HMA) was covered on the inner wall of the PVC pipe in different heights.

Synergistic catalytic effect of a composite (CoS/PEDOT:PSS) counter electrode on triiodide reduction in dye-sensitized solar cells.

Inorganic/organic nanocomposite counter electrodes comprised of sheetlike CoS nanoparticles dispersed in polystyrenesulfonate-doped poly(3,4-ethylenedioxythiophene (CoS/PEDOT:PSS) offer a synergistic effect on catalytic performance toward the reduction of triiodide for dye-sensitized solar cells (DSSCs), yielding 5.4% power conversion efficiency, which is comparable to that of the conventional platinum counter electrode (6.1%).