Information Storage Applications Research Articles

Ternary Memory Devices Based on Bipolar Copolymers with Naphthalene Benzimidazole Acceptors and Fluorene/Carbazole Donors

Functional polymers show great potential in information storage applications. However, most of these polymer-based memory devices demonstrate limited capacity because of binary memory characteristi...

Influence of ring position on the temporal dependence of charge movement in a switchable [2]rotaxane

AbstractSwitchable mechanically interlocked molecular architectures (MIMAs) are promising candidates for the components of nanoscale devices. An example of a MIMA‐based switch used in nanoscale devices is the electrochemically switchable Stoddart‐Heath‐type [2]rotaxane. This system's two coconformations differ in electrical conductance, a feature that has been harnessed for electronic and information storage applications. Herein we study the flow of charge in two coconformations of a bistable Stoddart‐Heath‐type [2]rotaxane and report statistical predictions of electron transfer times using a probabilistic approach for characterizing the timescale of quantum particle transit. The ratio of predicted transfer times for the two coconformations is consistent with the experimentally reported difference in electrical conductance. Path information offered by the probabilistic method gives insight into the influence of ring position on the mechanism of electron transit in this mechanically interlocked assembly.

Heartbeat-Sensing Mechanoluminescent Device Based on a Quantitative Relationship between Pressure and Emissive Intensity

Summary The pure organic mechanoluminescent luminogens (tPE-2-Th and tPE-3-Th), with their combination of aggregation-induced emission and the presence of a self-assembly unit, exhibit very bright mechanoluminescence (ML) emission even in daylight. Excitingly, the relationship between the pressure and ML intensity has been successfully established for the first time based on an ML device fabricated by tPE-2-Th. Furthermore, the flexible and wearable ML device demonstrates potential applications in communications, information storage, and health care. In particular, it provides a quick response to the human heartbeat, offering a new approach for the monitoring of force stimuli in daily life. Video Abstract Download : Download video (23MB)

Magnon dark mode in a strong driving microwave cavity

Inspired by the new discovery that the nonlinear dynamics of the cavity magnon polaritons have been observed with a small yttrium iron garnet (YIG) sphere (which introduces a nonlinear Kerr effect) placed into a microwave cavity, we theoretically study the nonlinear behaviors of the magnon dark mode without the magnon Kerr effect by inserting two YIG spheres into a microwave cavity under the strong driving field. The resulting bistability features of the magnon dark mode are sensitive to the frequency detuning between two YIGs and the magnetic field. Especially, when two YIGs have a finite frequency detuning, the magnon dark mode at the cavity resonance frequency does not display bistability. Our research not only sheds light on the nonlinear effect of the magnon dark mode in a strong driving field but also provides a theoretical basis for the application in information storage and novel spintronics.

Spatial-induced antiferromagnetic-like interaction of gadofullerene incarcerated in metal-organic-framework matrix

The ability to construct magnetic self-assembling architectures in carbon materials offers a novel and extremely tantalizing route towards spintronics, both from fundamental and application points of view. Endohedral metallofullerenes (EMFs) have been considered as a competitive candidate to achieve this goal due to their unique configuration and fascinating magnetism. In this work, a typical gadofullerene, Gd@C82-C2v, was successfully accommodated in the cavity of metal-organic frameworks (MOFs). The superconducting quantum interference device (SQUID) results unveiled an antiferromagnetic-like interaction of Gd@C82 with extremely enhanced paramagnetic moment. It was found that the confined effect of the aromatic fences of MOF matrix played a significant role in regulating the magnetic behavior of Gd@C82 molecules. Such a three-dimensional magnetic array of Gd@C82 would promote its application in high-density information storage and spintronic nanodevices.

Room-Temperature Active Modulation of Valley Dynamics in a Monolayer Semiconductor through Chiral Purcell Effects.

Spin-dependent contrasting phenomena at K and K' valleys in monolayer semiconductors have led to addressable valley degree of freedom, which is the cornerstone for emerging valleytronic applications in information storage and processing. Tunable and active modulation of valley dynamics in a monolayer WSe2 is demonstrated at room temperature through controllable chiral Purcell effects in plasmonic chiral metamaterials. The strong spin-dependent modulation on the spontaneous decay of valley excitons leads to tunable handedness and spectral shift of valley-polarized emission, which is analyzed and predicted by an advanced theoretical model and further confirmed by experimental measurements. Moreover, large active spectral tuning (≈24 nm) and reversible ON/OFF switching of circular polarization of emission are achieved by the solvent-controllable thickness of the dielectric spacer in the metamaterials. With the on-demand and active tunability in valley-polarized emission, chiral Purcell effects can provide new strategies to harness valley excitons for applications in ultrathin valleytronic devices.

Ramp secret sharing with cheater identification in presence of rushing cheaters

Abstract Secret sharing allows one to share a piece of information among n participants in a way that only qualified subsets of participants can recover the secret whereas others cannot. Some of these participants involved may, however, want to forge their shares of the secret(s) in order to cheat other participants. Various cheater identifiable techniques have been devised in order to identify such cheaters in secret sharing schemes. On the other hand, Ramp secret sharing schemes are a practically efficient variant of usual secret sharing schemes with reduced share size and some loss in security. Ramp secret sharing schemes have many applications in secure information storage, information-theoretic private information retrieval and secret image sharing due to producing relatively smaller shares. However, to the best of our knowledge, there does not exist any cheater identifiable ramp secret sharing scheme. In this paper we define the security model for cheater identifiable ramp secret sharing schemes and provide two constructions for cheater identifiable ramp secret sharing schemes. In addition, the second construction is secure against rushing cheaters who are allowed to submit their shares during secret reconstruction after observing other participants’ responses in one round. Also, we do not make any computational assumptions for the cheaters, i.e., cheaters may be equipped with unlimited time and resources, yet, the cheating probability would be bounded above by a very small positive number.

Control of light in a quantized four level graphene atomic system via self and cross-Kerr nonlinearity

Abstract We investigate self and cross-Kerr nonlinearity in a four level quantized graphene atomic medium. The absorption, dispersion, transmission and subluminal/superluminal behaviors of a probe light field are studied. An amplification of the probe light field is observed in the absorption spectrum. The normal and anomalous slope of dispersion is also investigated at the positive/negative absorption region. It is shown that Kerr nonlinearity invert and enhance the subluminal/superluminal behaviors of the pulse and self-Kerr effect is found to be more subluminal/superluminal as compared to cross-Kerr effect. The results show significant applications in information storage, self and cross phase modulation and lasing without inversion.

Photostimulated near-infrared persistent luminescence Cr3+-doped Zn-Ga-Ge-O phosphor with high QE for optical information storage

Near-infrared (NIR) persistent luminescence (PersL) phosphors, which exhibit unique properties of high signal-to-noise ratio and wide excitation spectral region, have attracted more and more attention in the next-generation high-capacity storage system. In this paper, a multi-spectral excited NIR PersL phosphor, Zn1.25Ga1.5Ge0.25O4: Cr3+ (ZGG: Cr3+) which is developed by doping ZnGa2O4: Cr3+ with tetravalent Ge4+, has been successfully synthesized. Rietveld refinements show that Ge4+ ions enter into octahedral sites by substituting Ga3+ ions and the hetero-valence substitution enriches the charged defects. This PersL phosphor exhibits a zero-phonon lines emission of Cr3+ [2E→4A2g] with the maximum at 698 nm and the maximum values of IQE and EQE can reach to 60.3% and 22.4%, respectively. An intense photostimulated persistent luminescence (PSPL) can be repeatedly obtained by NIR laser stimulation in a period of more than 48 h (write-out) when the ZGG: Cr3+ phosphor illuminated by an ultraviolet-light (UV) (write-in). In addition, adopting thermoluminescence (TL) method, we studied the electron motion in traps and found a specific PersL mechanism which will be reported in this work. All these results demonstrate that the ZGG: Cr3+ phosphor has promising applications in optical information storage.

ZnO/FLC nanocomposites with low driving voltage and non-volatile memory for information storage applications

Nanocomposites comprises of nano sized zinc oxide (ZnO, size ~10 nm) particles and ferroelectric liquid crystal (FLC) material have been prepared and studied. The concentration of the dopant (ZnO nanoparticles) in FLC matrix varied from 0.0 to 1 wt%. Distinct nanocomposites have been used to fabricate memory device and studied through dielectric spectroscopy, optical microscopy and electro-optical methods to explore electro-optic and memory parameters. Experimental results reveal that doping of ZnO nanoparticles in FLC leads to long lasting memory and low deriving voltage in nanocomposites. The achieved prolonged memory effect in nanocomposites may attribute to the charge transfer at the interfaces. Another reason, application of applied field may lead to ion trapping effect at ZnO surface which in turn minimize the depolarized field and enhance the memory effect in nanocomposites.

Magnetic Skyrmion Spectrum Under Voltage Excitation and its Linear Modulation

Magnetic skyrmions are topological quasiparticles with great potential for applications in future information storage and processing devices because of their nanoscale size, high stability, and large velocity. Recently, the high-frequency properties of skyrmions have been explored for magnon nanodevices. Here we systematically study the dynamics of an isolated skyrmion under voltage excitation through the voltage-controlled magnetic anisotropy effect in a circular thin film. A theoretical model considering the demagnetization energy, which has often been neglected or treated superficially in previous skyrmion research but is demonstrated to have importance in determining the skyrmion dynamic state, is developed. With our model, the periodic oscillation of the skyrmion radius can be solved numerically with similar precision compared to micromgnetic simulations, and the characteristic frequency of the skyrmion breathing can be determined analytically with greater precision than previous studies. Furthermore, we find that the breathing skyrmion can be analogized as a modulator by investigating its linear modulation functionality under sinusoidal-form voltage excitation. Different from the conventional modulation system with complex CMOS circuits, this skyrmion modulator device integrates with both the modulation and carrier wave generation functionality, thus showing greater convenience and efficiency in applications. Our findings can provide useful guidance for both theoretical and experimental skyrmions research as well as the development of skyrmion-based magnonic devices with significant potential applicability in future communication system.

Structure and photoluminescence properties of Dy3+ doping in Sr-Si-O-N frameworks for highly efficient white light and optical information storage applications

A series of Dy3+ doped Sr-Si-O-N frameworks with single phase were successfully developed by a two-step synthetic method. Under excitation of NUV light, Dy3+ singly-doped SrSi2O2N2 (a typical Sr-Si-O-N framework) phosphors exhibited two emission peaks at 478 nm and 571 nm, corresponding to blue (4F9-2→6H15-2) and yellow (4F9-2→6H13-2) emissions of Dy3+ ions. Compared with the traditional solid state reaction, the two-step method facilitated the formation of SrSi2O2N2: Dy3+ phosphor with pure phase and greatly enhanced the photoluminescence emission intensity (~4 times). The emission intensities of SrSi2O2N2: xDy3+ phosphors reached the maximum when x = 0.06 due to the concentration quenching, which was confirmed to be electric dipole-electric dipole interaction. The SrSi2O2N2: Dy3+ phosphors with an excellent thermal stability can be regarded as the potential single phase white-light phosphors when excited by NUV light. The optimal chromaticity coordinate of white light is (0.3347, 0.3966) for SrSi2O2N2: 0.06Dy3+ phosphor. Interestingly, the single green emission band at 525 nm was observed and a unique thermo-stimulated luminescence property was demonstrated for Dy3+/Eu2+ co-doped SrSi2O2N2 phosphors. A specific photographic pattern (for example pentagon pattern) was obtained by covered the mask on the surface of SrSi2O2N2: Eu2+, Dy3+ pellets under excitation of UV light. After UV lights turn off, the pentagon patterns were reproduced by heating the SrSi2O2N2: Eu2+, Dy3+ pellets. It was validated from the decrease of PL emission intensity and decay time with the increasing Dy3+ content that Dy3+ ions were acted as the deep trap centers. Similar thermal-stimulated luminescence was also found for Eu2+ singly-doped SrSi2O2N2 phosphor due to the oxygen vacancy in host lattice. Furthermore, the mechanism of thermal-stimulated luminescence has been proposed and Dy3+/Eu2+ co-doped SrSi2O2N2 phosphors with deep traps are suitable to be the good candidates for optical information storage applications.

Asymmetric coding metasurfaces for the controllable projection of acoustic images

The projection of acoustic images is of relevance for a wide range of applications, including acoustic communication and medical imaging. Various acoustic projection devices that use holograms have been proposed; however, they inevitably involve multiple basic elements and lack reconfigurability. In this paper, we demonstrate that an acoustic coding metasurface that consists of a single type of asymmetric acoustic unit (AAU) can be used to project the desired acoustic images. The AAU is constructed using a perforated panel and coating unit cell, which can be tunable in terms of the transmission coefficient and reflection phase asymmetry. Patterned in regular and inverse forms, the AAU can function as the coding elements ``0'' and ``1,'' respectively. We demonstrate, both numerically and experimentally, the efficient projection of complex acoustic images such as the letters ``N,'' ``J,'' and ``U.'' More importantly, we develop a simple composite metasurface system to achieve the controllable encryption and decryption of acoustic images. Our proposed approach provides a design methodology for the coding metasurface and may have applications in acoustic security, information storage, and wave manipulation.

One Stimulus In Situ Induces Two Sequential Luminescence Switchings in the Same Solvent‐Fuming Process: Anthracene Excimer as the Intermediate

AbstractCommonly, one stimulus only induces one luminescence switching in stimuli‐responsive experiment. Herein, it is reported that one stimulus in situ induces two luminescent switches, resulting from two phase transitions in a solvent‐fuming process. Two phase transitions are in situ composed of a first fast and a subsequent slow process, corresponding to the change of molecular packing from the amorphous state to the π–π dimer crystalline state to the cocrystalline state with the inclusion of solvents, accompanied with luminescent transformation from pure blue to green to deep blue. Theoretical and experimental results reveal that the staggered π–π dimer stacking of anthracenes serves as the intermediate state to bridge the two phase transitions. This finding expands a new horizon in the stimuli‐responsive field and inspires novel applications in information storage and security fields.

Convertible Insulator–Conductor Transition in Silver Nanowire Networks: Engineering the Nanowire Junctions

Achieving a switchable conductance in metallic nanowire networks is of great importance for applications in wearable electronics, selectors, information storage, and neuromorphic computing. However...

Synthesis and Characterization of Copper Oxide Nanoparticles (CuO NPs) using Mangifera indica Leaf Extract

Metal oxide nanoparticles (NPs) receiving a significant consideration for their probable applications in nanodevices, optoelectronics, nanosensors, nanoelectronics, catalysis and information storage. The objective of the work was to be investigate the synthesis of CuO NPs and evaluation of its characterization of CuO NPs using leaf extract of <i>Mangifera indica</i>. <i>Mangifera indica</i> leaf extract was found suitable for the copper oxide nanoparticles synthesis through biological method ambient conditions. Spherical, polydispersity of CuO NPs of particle sizes ranging from 18 to 106 nm. The average size was 52.54 nm. The formation of color changes indicates that the synthesis of CuO NPs due to plasmon resonance with the active compounds present in the <i>Mangifera indica</i> leaf extract. CuO NPs further confirmed by FT-IR, UV–vis spectroscopy, XRD, EDX and SEM. The functional groups confirmed that the alcohol, phenol, aromatics and alkynes have a probable adherence capacity with copper oxide, which acting as a capping agent and responsible for the bioreduction process.<div><br></div>

Temperature‐dependent electrical transport behavior and structural evolution in hollandite‐type titanium‐based oxide

AbstractElectrical transport behavior and structural characteristics directly determine the use of functional ceramic materials in electronic information storage, catalytic conversion, and energy field applications. However, these properties are poorly understood because most of the relevant experiments were performed in a rather narrow temperature range. Herein, we used hollandite‐type KxTi8O16 as an example to systematically study the temperature‐dependent structure and electrical transport properties in a wide temperature range from 25 to 900°C. The electrical transport involves both potassium ionic conduction and electronic conduction. With increasing temperature, the ionic conductivity increases below 800°C and decreases above 800°C. The electronic conductivity displays two maxima at 0.15 S/cm at 400°C and 5.2 × 10−4 S/cm at 800°C. These interesting variations in the conductivities are related to the presence of Ti3+ and the structural transformation from hollandite to a mixture of rutile and jeppeite. The findings reported herein support the potential application of titanium‐based hollandites and provide an understanding of the electrical transport properties of functional ceramic materials.

New physical insight in structural and electronic properties of InSb nano-sheet being rolled up into single-wall nanotubes

The structure evolution and the electronic properties of InSb monolayers and nanotubes were thoroughly studied by first-principles theory. The results showed that InSb monolayer exhibits intrinsic electric polarization of 12 pC/m, and the direction of electric polarization can be switched when strain or external electric fields are applied. InSb monolayer has a high electron and hole-mobility of ~7 × 103 and 0.7 × 102, respectively. When the monolayer is rolled up to form nanotubes, the optimized parameters, energy level, and electronic structure, were calculated for the armchair and the zigzag configurations. The calculated electronic structure shows that the monolayer has a direct band gap of 1.29 eV, while after being rolled up into small diameter InSb [6] and InSb (6,0) nanotubes, there is an increase of the band gap to 1.58 and 1.70 eV for the two aforementioned configurations, respectively. Furthermore, the strain energy of the nanotubes is lower than that of the monolayer. The increase of band gap when the monolayer was rolled up into nanotubes was attributed to p-p coupling between In-3p orbital in the conduction band of InSb in nanotubes. The findings of the present work suggest that InSb monolayer may have observable ferroelectricity; thus, it can qualify for consideration in information storage applications.

Ammonium-Induced Synthesis of Highly Fluorescent Hydroxyapatite Nanoparticles with Excellent Aqueous Colloidal Stability for Secure Information Storage

In this paper, uniform hydroxyapatite (HA) nanoparticles, with excellent aqueous colloidal stability and high fluorescence, have been successfully synthesized via a citrate-assisted hydrothermal method. The effect of the molar ratio of ammonium phosphate in phosphate (RAMP) and hydrothermal time on the resultant products was characterized in terms of crystalline structure, morphology, colloidal stability, and fluorescence behavior. When the RAMP is 50% and the hydrothermal time is 4 h, the product consists of a pure hexagonal HA phase and a uniform rod-like morphology, with 120- to 150-nm length and approximately 20-nm diameter. The corresponding dispersion is colloidally stable, and transparent for at least one week, and has an intense bright blue emission (centered at 440 nm, 11.6-ns lifetime, and 73.80% quantum efficiency) when excited by 340-nm UV light. Although prolonging the hydrothermal time and increasing the RAMP had no appreciable effect on the aqueous colloidal stability of HA nanoparticles, the fluorescence intensity was enhanced. The cause of HA fluorescence are more biased towards carbon dots (which are mainly polymer clusters and/or molecular fluorophores constituents) trapped in the hydroxyapatite crystal structure. Owing to these properties, a highly fluorescent HA colloidal dispersion could find applications in secure information storage.

Spin Selectivity in Photoinduced Charge-Transfer Mediated by Chiral Molecules.

Optical control and readout of electron spin and spin currents in thin films and nanostructures have remained attractive yet challenging goals for emerging technologies designed for applications in information processing and storage. Recent advances in room-temperature spin polarization using nanometric chiral molecular assemblies suggest that chemically modified surfaces or interfaces can be used for optical spin conversion by exploiting photoinduced charge separation and injection from well-coupled organic chromophores or quantum dots. Using light to drive photoexcited charge-transfer processes mediated by molecules with central or helical chirality enables indirect measurements of spin polarization attributed to the chiral-induced spin selectivity effect and of the efficiency of spin-dependent electron transfer relative to competitive relaxation pathways. Herein, we highlight recent approaches used to detect and to analyze spin selectivity in photoinduced charge transfer including spin-transfer torque for local magnetization, nanoscale charge separation and polarization, and soft ferromagnetic substrate magnetization- and chirality-dependent photoluminescence. Building on these methods through systematic investigation of molecular and environmental parameters that influence spin filtering should elucidate means to manipulate electron spins and photoexcited states for room-temperature optoelectronic and photospintronic applications.