Inverted Domain Research Articles

MAGI-1a Functions as a Scaffolding Protein for the Distal Renal Tubular Basolateral K+ Channels

As the K(+) recycling pathway for renal Na(+) reabsorption, renal tubular K(+) channels participate in the fluid and electrolyte homeostasis. Previously, we showed that the Kir5.1/Kir4.1 heteromer, which is a heteromeric assembly of two inwardly rectifying K(+) channels, composes the principal basolateral K(+) channels in distal renal tubules and that two motifs in the carboxyl-terminal portion of the Kir4.1 subunit regulate its functional expression. In this study, by using yeast two-hybrid screening, we identified a new isoform of membrane-associated guanylate kinase with inverted domain structure 1 (MAGI-1a-long) as a scaffolding protein for the basolateral K(+) channels. MAGI-1a-long interacted with the PSD-95/Dlg/ZO-1 (PDZ)-binding motif of Kir4.1 by its fifth PDZ domain, and a high salt diet, which could suppress mineralocorticoid secretion, facilitated the interaction. The phosphorylation of serine 377 in the PDZ-binding motif disrupted the interaction, and the disruption of the interaction altered the intracellular localization of the channels from the basolateral side to perinuclear components. These results demonstrate that the phosphorylation-dependent scaffolding of the basolateral K(+) channels by MAGI-1a-long participates in the renal regulation of the fluid and electrolyte homeostasis.

Optical interference in nonlinear photonic crystals

A model to analyze the interaction of the parametric fields being generated in a two-dimensional nonlinear photonic crystal has been developed. The analysis provides details of the interference of the generated wave(s) both inside and in the region just outside the crystal. The results are verified by second-harmonic generation in a LiNbO3 crystal that has been poled with a tetragonal inverted domain structure.

Ferroelectric Domain Breakdown

A new phenomenon—ferroelectric domain breakdown, or the formation of string-like domains—is observed in various bulk ferroelectric crystals under a high inhomogeneous electric field generated at the tip of a high-voltage atomic force microscope. The domains have a high aspect ratio when their length exceeds their lateral size by two or three orders of magnitude. This chapter reviews some of the recent advances in understanding the nature of this phenomenon. The main driving force for ferroelectric domain breakdown is not the tip's electric field, which is negligibly weak near the apex of the long domain, but rather internal forces generated owing to the minimization of depolarization field energy when the domain elongates. Domain breakdown is considered an extreme manifestation of Coulomb instability, which is caused by repulsion of bound charges near the inverted domain apex. This instability leads to strong pulling of the domain apex into a region where the tip-induced electric field is negligibly small.

Photolithography by a tunable electro-optical lithium niobate phase array

Photolithography experiments are performed by means of an optical phase mask with electrooptically tunable phase step. The phase mask consists of a 2-dimensional hexagonal lattice of inverted ferroelectric domains fabricated on a z-cut lithium niobate substrate. The electro-optically tunable phase step, between inverted domain, is obtained by the application of an external electric field along the z axis of the crystal via transparent electrodes. The collimated beam of an argon laser passes through the phase mask and the near field intensity patterns, at different planes of the Talbot length and for different values of the applied voltage, are used for photolithographic experiments. Preliminary results are shown and further applications are discussed.

Stabilization of periodically poled domain structures in a quasiphase-matching device using near-stoichiometric LiTaO 3

The stability of periodically poled domain structures in near-stoichiometric lithium tantalite, LiTaO3, (SLT) crystals exhibiting a low coercive field has become an important issue in the use of quasiphase-matching (QPM) devices. Temperature-induced backswitching in inverted domain structures in a 1.0 mol % MgO-doped SLT-QPM device with a QPM period of 6.1 μm used for the second harmonic generation of 488-nm-wavelength light was investigated using scanning force microscopy. It was revealed that backswitching consistently occurred due to heat treatment and that the amount was dependent on the temperature history. We propose an effective method of suppressing backswitching in the inverted domain structures of SLT-QPM devices on the basis of systematically analyzing the backswitching phenomena.

Nanodomain manipulation for ultrahigh density ferroelectric data storage

Nanosized inverted domain dots in ferroelectric materials have potential application inultrahigh density rewritable data storage systems. Herein, a data storage system ispresented based on scanning non-linear dielectric microscopy and a thin film offerroelectric single-crystal lithium tantalite. Through domain engineering, wesucceeded in forming our smallest artificial nanodomain single dot at 5.1 nmdiameter and an artificial nanodomain dot array with a memory density of10.1 Tbit inch−2 and a bit spacing of 8.0 nm, representing the highest memory density for rewritabledata storage reported to date. Subnanosecond (500 ps) domain switching speedhas also been achieved. Next, actual information storage with a low biterror and high memory density was performed. A bit error ratio of less than1 × 10−4 was achieved atan areal density of 258 Gbit inch−2. Moreover, actual information storage is demonstrated at a density of1 Tbit inch−2.

AFM based polarization nanolithography on PZT sol–gel films

In this work, the possibility to create the inverted domain patterns on the surface of sol–gel derived ferroelectric PbTiO 3–PbZrO3 (PZT) thin films are demonstrated. Surface microstructure and local piezoelectric properties were investigated by piezoresponse atomic force microscopy. Macroscopic piezoelectric properties are investigated by laser Doppler vibrometry. PZT films exhibits high d 33 (93 pm/V in unpoled and 419 pm/V in poled state). Piezoresponse atomic force microscope (AFM) measurements were carried out by applying AC voltage (frequency 25 kHz and amplitude of 2 V) coupled with DC bias voltage between the grounded tip of AFM and Pt bottom electrode of the sample, and detecting first harmonics of resulting surface vibration by lock-in amplifier. The possibility to write and read the polarization patterns on the PZT thin film by piezoresponse AFM was confirmed.

Realization of 10Tbit∕in.2 memory density and subnanosecond domain switching time in ferroelectric data storage

Nanosized inverted domain dots in ferroelectric materials have potential application in ultrahigh-density rewritable data storage systems. Herein, a data storage system is presented based on scanning nonlinear dielectric microscopy and a thin film of ferroelectric single-crystal lithium tantalite. Through domain engineering, nanosized inverted domain dots have been successfully formed at a data density above 10.1Tbit∕in.2 and subnanosecond (500ps) domain switching speed has been achieved. Moreover, actual information storage is demonstrated at a density of 1Tbit∕in.2

MAGI-1 is a component of the glomerular slit diaphragm that is tightly associated with nephrin

MAGUK with inverted domain structure-1 (MAGI-1) is a membrane-associated protein with one guanylate kinase, six PSD-95/Dlg-A/ZO-1 (PDZ), and two WW domains and is localized at tight junctions in epithelial cells. MAGI-1 interacts with various proteins and is proposed to function as a scaffold protein. In the previous study, we discovered a MAGI-1-interacting cell adhesion molecule junctional adhesion molecule 4 (JAM4). Both proteins are highly expressed in glomerular podocytes in the kidney and partially colocalized. In this study, we have further searched for a binding partner of MAGI-1 in the kidney through yeast two-hybrid screening and obtained nephrin. Nephrin is a cell adhesion molecule specifically localized at the slit diaphragm between neighboring foot processes of podocytes. Biochemical studies reveal that nephrin directly binds to the middle PDZ domains of MAGI-1 through its carboxyl terminus but does not bind to ZO-1. MAGI-1 forms a tripartite complex with nephrin and JAM4 in vitro. Immunoelectron microscopy shows that the localization of MAGI-1 is restricted to the slit diaphragm, whereas JAM4 is also distributed on apical membranes of podocytes. In puromycin aminonucleoside-induced nephrotic podocytes, MAGI-1 is localized with nephrin at the displaced slit diaphragm. These data indicate that MAGI-1 is a component of the slit diaphragm and tightly interacts with nephrin and JAM4 in vivo. MAGI-1 may play a role in determining the boundary between the apical and the bosolateral domain at the level of slit diaphragm.

Ultrahigh-Density Ferroelectric Data Storage Based on Scanning Nonlinear Dielectric Microscopy

Ferroelectrics have generated considerable interest as promising storage media. In this paper, an investigation of ultrahigh-density ferroelectric data storage based on scanning nonlinear dielectric microscopy (SNDM) is described. For the purpose of obtaining fundamental knowledge on high-density ferroelectric data storage, several experiments on nanodomain formation in a lithium tantalate (LiTaO3) single crystal were conducted. As a result, a very small inverted domain with a radius of 6 nm was successfully formed in stoichiometric LiTaO3 (SLT), and a domain dot array with an areal density of 1.5 Tbit/in.2 was formed on congruent LiTaO3 (CLT). Moreover, it was found that fast nanosecond domain switching could be achieved by reducing the thickness of a CLT plate sample. Additionally, the prototype high-density ferroelectric data storage system was developed. Using this system, writing data transfer rates were evaluated and 256×256 bit data were recorded with the areal densities of 258 and 717 Gbit/in.2

EO probe for simultaneous electric and magnetic near-field measurements using LiNbO/sub 3/ with inverted domain

This paper presents a new type of optical probe for simultaneous measurements of electric and magnetic near fields with high accuracy up to the gigahertz range. Its probe head consists of a loop antenna element that is doubly loaded with LiNbO3 electrooptic crystals. Using optical technology, it can work as a conventional double-loaded loop probe without metallic cables and electrical hybrid junction. We examined probe characteristics for electromagnetic field detection up to 20 GHz. We confirmed that the probe can measure electric and magnetic fields simultaneously with a high accuracy in the gigahertz range

Super High-Density Ferroelectric Data Storage using Scanning Nonlinear Dielectric Microscopy

Ferroelectrics has generated considerable interest as promising storage media. In this paper, an investigation of ultrahigh-density ferroelectric data storage based on scanning nonlinear dielectric microscopy (SNDM) was carried out. For the purpose of obtaining fundamental knowledge of high-density ferroelectric data storage, several experiments on nanodomain formation in lithium tantalate (LiTaO3) single crystal were conducted. As a result, a very small inverted domain with a radius of 6 nm was successfully formed in stoichiometric LiTaO3 (SLT), and in addition, a domain dot array with an areal density of 1.5 Tbit/inch2 was formed on congruent LiTaO3 (CLT). Moreover, it was found that fast nanosecond domain switching could be achieved by reducing the sample thickness of CLT plate. Additionally, the first prototype high-density ferroelectric data storage system was developed. Using this system, writing data transfer rates were evaluated and 256×256 bit data were recorded with the areal densities of 258 Gbit/inch2 and 717 Gbit/inch2.

Nanosecond Switching of Nanoscale Ferroelectric Domains in Congruent Single-Crystal LiTaO3 Using Scanning Nonlinear Dielectric Microscopy

The domain switching characteristics of a congruent LiTaO3 (CLT) single crystal are investigated mainly with respect to switching speed. It is found that fast nanosecond domain switching can be achieved by reducing the sample thickness, even for CLT, which has been thought to be unsuitable for high-speed switching. As an example, the authors successfully obtain a polarization inverted domain dot with a radius of 7.9 nm in a 60-nm-thick CLT plate by application of a 4 ns, 10 V pulse. These results demonstrate that the speed of polarization reversal is closely related to the thickness of the medium.

Perfectly c-axis oriented epitaxial lead titanate thin film deposited by a hydrothermal method for a data storage medium

ABSTRACTA hydrothermal method is a unique method to deposit ferroelectric thin films utilizing chemical reaction in solutions. In addition to the low reaction temperature below 200°C, its simple process procedure, automatically aligned polarization and a three-dimensional deposition are advantages. In this study, a lead titanate epitaxial thin film was obtained on a strontium ruthenate bottom electrode sputterd on strontium titanate (100). The highresolution X-ray diffraction mapping showed the film was perfectly c-axis oriented. The transmission electron microscope observation revealed that the film had no lattice dislocation at the interface between lead titanate and strontium ruthenate. A remanent polarization of 96.5μC/cm2 was measured with the single crystal-like DE hysteresis curve. The observation of a scanning nonlinear dielectric microscopy indicated that this film did not contain any defect such as an a-domain and a grain boundary even on the nano scale. With various pulse parameters, nano-domain dots were patterned and the minimum dot radius of inverted domain was 12 nm corresponding to data storage density of 1Tbit/inch2.

A Hydrothermally Deposited Epitaxial PbTiO3 Thin Film on SrRuO3 Bottom Electrode for the Ferroelectric Ultra-High Density Storage Medium

A lead titanate epitaxial thin film is one of the important ferroelectric films and lattice matching with strontium titanate is preferable. However, it was thought to be difficult to obtain high insulation property and very few superior hysteresis curves were measured with lead titanate. The hydrothermal method can avoid a lead vacancy and residual strain at the boundary of the substrate due to low reaction temperature of 150°C. Using strontium ruthenium oxide bottom electrode on strontium titanate, the lead titanate thin film was successfully deposited by the hydrothermal method. The single crystal-like DE hysteresis curve showed a remanent polarization of 96.5 μ C/cm2. The domain direction was controlled by an applied electric field using a metal coated AFM cantilever probe and the domain pattern was observed by scanning nonlinear dielectric microscopy (SNDM). Minimum dot radius of inverted domain was 12 nm corresponding to data storage density of 1 Tbit/inch2.

High-speed switching of nanoscale ferroelectric domains in congruent single-crystal LiTaO3

The nanodomain reversal characteristics of congruent LiTaO3 (CLT) single crystal are investigated. It is found that fast nanosecond domain switching can be achieved by reducing the sample thickness, even for CLT, which contains many Li vacancy defects that pin domain-wall movement. As an example, the authors obtain a polarization inverted domain dot with a radius of 7.9 nm by application of a 4 ns 10 V pulse. These results demonstrate that the speed of polarization reversal is closely related to the thickness of the medium.

Scanning Nonlinear Dielectric Microscopy : Overview -A High Resolution Tool for Observing Ferroelectric Domains and Nano-domain Engineering-

A sub-nanometer resolution Scanning Nonlinear Dielectric Microscope (SNDM) was developed for observing ferroelectric polarization. We also demonstrate that the resolution of SNDM is higher than that of a conventional piezo-response imaging. Secondly, we report new SNDM technique detecting higher nonlinear dielectric constants e 3333 and e 33333 . Higher order nonlinear dielectric imaging provides higher lateral and depth resolution. Finally, the formation of artificial small inverted domain is reported to demonstrate that SNDM system is very useful as a nano-domain engineering tool. The nano-size domain dots were successfully formed in LiTaO₃ single crystal. This means that we can obtain a very high density ferroelectric data storage with the density above 1T-bits/inch².

Ultrahigh-Density Ferroelectric Data Storage Using Scanning Nonlinear Dielectric Microscopy

Ferroelectrics have generated considerable interest as promising storage media. In this paper, an investigation of ultrahigh-density ferroelectric data storage based on scanning nonlinear dielectric microscopy (SNDM) was carried out. For the purpose of obtaining fundamental knowledge of high-density ferroelectric data storage, several experiments on nanodomain formation in lithium tantalate (LiTaO3) single crystal were conducted. As a result, a very small inverted domain with a radius of 6 nm was successfully formed in stoichiometric LiTaO3 (SLT), and in addition, a domain dot array with an areal density of 1.5 Tbit/inch2 was written on congruent LiTaO3 (CLT). Additionally, the first prototype high-density ferroelectric data storage system was developed. Using this system, reading and writing data transfer rates were evaluated.

Tbit/Inch 2 Data Storage Using Scanning Nonlinear Dielectric Microscopy

Nano-sized inverted domain dots in ferroelectric materials is a technology with potential applications in ultrahigh-density rewritable data storage systems. Up to now, we have studied domain inversion characteristics of stoichiometric and congruent LiTaO 3 single crystals in nanoscopic area using scanning nonlinear dielectric microscopy (SNDM), which is the technique for observing ferroelectric polarization distribution with sub-nanometer resolution. In this study, we have revealed nano-sized inverted domain remained stably for a long time, and successfully formed inverted domain dots at a data density of 1.50 Tbit/inch 2, representing the highest memory density for rewritable electric data storage reported to date.

Surface Domain Inversion in Ferroelectric Lithium Niobate

Periodic inversion is reported for ferroelectric domains near the surface of z-cut lithium niobate crystals by a modified electric field poling technique. The depth of the inverted domain region extends to values of order a few μm (5–10 μm) below the surface of the crystal, thereby removing the high aspect ratio instability problems associated with bulk poling, and therefore allowing the fabrication of fine period ferroelectric domain structures. Using this method periods as short as 1 μm have been achieved. Such periodic domain distributions have been fabricated in Ti-indiffused and proton exchanged lithium niobate waveguides and our first quasi-phase-matching results are shown.