Atomic Origins of Enhanced Ferroelectricity in Nanocolumnar PbTiO /PbO Composite Thin Films.

Nanocomposite films hold great promise for multifunctional devices by integrating different functionalities within a single film. The microstructure of the precipitate/secondary phase is an essential element in designing composites' properties. The interphase strain between the matrix and secondary phase is responsible for strain-mediated functionalities, such as magnetoelectric coupling and ferroelectricity.

Anisotropic Melting Path of Charge-Ordering Insulator in LSMO/STO Superlattice.

Multiple phases coexist in manganite with simultaneously active couplings, and the transition among them depends on the relative intensities of different interactions. However, the melting path with variable intensities is unclear. The concentration and the ordering of oxygen vacancy in previous work are found to induce ferromagnetic charge-ordering insulator phase in [(La Sr MnO ) /(SrTiO ) ] superlattice, which translates into metallic phase with magnetic field H and temperature T.

Large-Scale Epitaxial Growth of Ultralong Stripe BiFeO Films and Anisotropic Optical Properties.

The controlled synthesis of large-scale ferroelectric domains with high uniformity is crucial for practical applications in next-generation nanoelectronics on the basis of their intriguing properties. Here, ultralong and highly uniform stripe domains in (110)-oriented BiFeO thin films are large-area synthesized through a pulsed laser deposition technique. Utilizing scanning transmission electron microscopy and piezoresponse force microscopy, we verified that the ferroelectric domains have one-dimensional 109° domains and the length of a domain is up to centimeter scale.

Ferroelectric Self-Polarization Controlled Magnetic Stratification and Magnetic Coupling in Ultrathin LaSrMnO Films.

Multiferroic oxide heterostructures consisting of ferromagnetic and ferroelectric components hold the promise for nonvolatile magnetic control via ferroelectric polarization, advantageous for the low-dissipation spintronics. Modern understanding of the magnetoelectric coupling in these systems involves structural, orbital, and magnetic reconstructions at interfaces. Previous works have long proposed polarization-dependent interfacial magnetic structures; however, direct evidence is still missing, which requires advanced characterization tools with near-atomic-scale spatial resolutions.

Perovskite Light-Emitting Diodes with Near Unit Internal Quantum Efficiency at Low Temperatures.

Room-temperature-high-efficiency light-emitting diodes based on metal halide perovskite FAPbI are shown to be able to work perfectly at low temperatures. A peak external quantum efficiency (EQE) of 32.8%, corresponding to an internal quantum efficiency of 100%, is achieved at 45 K.

Tuning Irreversible Magnetoresistance in PrSrMnO Film via Octahedral Rotation.

The oxygen octahedral rotation around the out-of-plane axis is explored to study its effect on metastable status, magnetic cluster glass in manganite. The antiphase rotation around the out-of-plane axis (TiO ) of SrTiO enhances the Mn-O bond anisotropy along in-plane and out-of-plane directions and weakens the ferromagnetic interactions in a 12 nm PrSrMnO film on the (001) SrTiO substrate, which together promote the formation of magnetic cluster-glassiness and enlarges the irreversible magnetoresistance (MR) effect with enhanced relaxation time of charge carriers. The effect of TiO in the SrTiO substrate on material properties is obvious with a large irreversible MR effect for thin films, which fades away with the increase in film thickness.

Magnetoelectric Coupling Induced Orbital Reconstruction and Ferromagnetic Insulating State in PbZrTiO/LaSrMnO Heterostructures.

Novel phenomena at the ferromagnetic/ferroelectric interface have generated much interest. Here, a ferromagnetic insulating state with the Curie temperature about 268-286 K in PbZrTiO/LaSrMnO heterostructures is induced and modulated by varying the PbZrTiO thickness. An abnormally enlarged / ratio in LaSrMnO by strain-based coupling effect leads to orbital preferable occupancy.

Perpendicular Magnetic Anisotropy and Dzyaloshinskii-Moriya Interaction at an Oxide/Ferromagnetic Metal Interface.

We report on the study of both perpendicular magnetic anisotropy (PMA) and Dzyaloshinskii-Moriya interaction (DMI) at an oxide/ferromagnetic metal (FM) interface, i.e., BaTiO_{3} (BTO)/CoFeB.

Overcoming the Limits of the Interfacial Dzyaloshinskii-Moriya Interaction by Antiferromagnetic Order in Multiferroic Heterostructures.

Topologically protected magnetic states have a variety of potential applications in future spintronics owing to their nanoscale size (<100 nm) and unique dynamics. These fascinating states, however, usually are located at the interfaces or surfaces of ultrathin systems due to the short interaction range of the Dzyaloshinskii-Moriya interaction (DMI). Here, magnetic topological states in a 40-unit cells (16 nm) SrRuO layer are successfully created via an interlayer exchange coupling mechanism and the interfacial DMI.

Atomic-Scale Control of Magnetism at the Titanite-Manganite Interfaces.

Complex oxide thin-film heterostructures often exhibit magnetic properties different from those known for bulk constituents. This is due to the altered local structural and electronic environment at the interfaces, which affects the exchange coupling and magnetic ordering. The emergent magnetism at oxide interfaces can be controlled by ferroelectric polarization and has a strong effect on spin-dependent transport properties of oxide heterostructures, including magnetic and ferroelectric tunnel junctions.

Emergence of Topological Hall Effect in a SrRuO Single Layer.

Topological Hall effect (THE), appearing as bumps and/or dips in the Hall resistance curves, is considered as a hallmark of the skyrmion spin texture originated from the inversion symmetry breaking and spin-orbit interaction. Recently, Néel-type skyrmion is proposed based on the observed THE in 5d transition metal oxides heterostructures such as SrRuO /SrIrO bilayers, where the interfacial Dzyaloshinskii-Moriya interaction (DMI), due to the strong spin-orbit coupling (SOC) in SrIrO and the broken inversion symmetry at the interface, is believed to play a significant role. Here the emergence of THE in SrRuO single layers with thickness ranging from 3 to 6 nm is experimentally demonstrated.

Control of Synaptic Plasticity Learning of Ferroelectric Tunnel Memristor by Nanoscale Interface Engineering.

Brain-inspired computing is an emerging field, which intends to extend the capabilities of information technology beyond digital logic. The progress of the field relies on artificial synaptic devices as the building block for brainlike computing systems. Here, we report an electronic synapse based on a ferroelectric tunnel memristor, where its synaptic plasticity learning property can be controlled by nanoscale interface engineering.

Interfacial Coupling-Induced Ferromagnetic Insulator Phase in Manganite Film.

Interfaces with subtle differences in atomic and electronic structures in perovskite ABO3 heterostructures often yield intriguingly different properties, yet their exact roles remain elusive. Here, we report an integrated study of unusual transport, magnetic, and structural properties of Pr0.67Sr0.

Effects of strain relaxation in Pr0.67Sr0.33MnO3 films probed by polarization dependent X-ray absorption near edge structure.

The Mn K edge X-ray absorption near edge structure (XANES) of Pr0.67Sr0.33MnO3 films with different thicknesses on (001) LaAlO3 substrate was measured, and the effects of strain relaxation on film properties were investigated.

Strain Engineering of Octahedral Rotations and Physical Properties of SrRuO3 Films.

Strain engineering is an effective way to modify functional properties of thin films. Recently, the importance of octahedral rotations in pervoskite films has been recognized in discovering and designing new functional phases. Octahedral behavior of SrRuO3 film as a popular electrode in heterostructured devices is of particular interest for its probable interfacial coupling of octahedra with the functional overlayers.

Facile patterning of upconversion NaYF4:Yb,Er nanoparticles.

Different kinds of highly ordered patterns of NaYF(4):Yb,Er nanoparticles on gold substrates were fabricated using a simple method combining micro-contact printing and "breath figures" techniques. Ordered arrays of water droplets were first formed in the hydrophilic regions of patterned self-assembled monolayers (SAMs). This was subsequently submerged in a chloroform solution of NaYF(4):Yb,Er nanoparticles.

Interfacial properties and in vitro cytotoxic effects of surface-modified near infrared absorbing Au-Au(2)S nanoparticles.

Near infrared (NIR) absorbing Au-Au(2)S nanoparticles were modified with surfactants of different hydrocarbon chain lengths to allow loading of anticancer drug, cisplatin. The interfacial interactions and surfactant chain length effects on drug loading, optical properties and cytotoxicity were discussed in this work. Short-chain surfactants were oriented closer to the surface normal and were adsorbed at higher densities.

Effects of oleic acid surface coating on the properties of nickel ferrite nanoparticles/PLA composites.

Nickel ferrite nanoparticles with or without oleic acid surface coating were mixed with poly(D,L-lactide) (PLA) by double emulsion method. If the nanoparticles were prepared without oleic acid coating, they adsorbed on the PLA surface. If the nanoparticles were coated with oleic acid, they could be readily encapsulated within the PLA microspheres.

Engineering inorganic hybrid nanoparticles: tuning combination fashions of gold, platinum, and iron oxide.

Multistep colloidal chemical routes were employed to synthesize Pt/Au, Pt/iron oxide (IO), and Au/Pt/IO hybrid nanoparticles (NPs). The starting templates, Pt NPs, were synthesized by controlling the decomposition kinetics of platinum acetylacetonate in oleylamine. The morphologies of binary metal Pt/Au hybrid NPs were modulated by controllable attachment of Au nanoscale domains to Pt templates.

Morphological control of synthesis and anomalous magnetic properties of 3-D branched Pt nanoparticles.

Morphology-controllable platinum nanostructures could be obtained by modulating the growth kinetics in oleylamine. The nanostructures evolve from spherical particles to branched networks with decreasing reaction temperature, and the complexity of the branched-network nanostructures increases with the extended reaction period. Size-dependent magnetic properties and enhanced ferromagnetism in dodecanethiol-capped Pt branched nanostructures indicate that the permanent magnetic moments are probably introduced by broken symmetry and charge transfer because charge transfers more effectively from dodecanethiol than from oleylamine.

Cisplatin-loaded Au-Au2S nanoparticles for potential cancer therapy: cytotoxicity, in vitro carcinogenicity, and cellular uptake.

Cisplatin is one of the most effective cytotoxic agents against cancers. Its usage, however, is limited because of severe resistance and systemic toxicity. A formulation of cisplatin-loaded Au-Au(2)S nanoparticles (NPs) with near-IR (NIR) sensitivity is reported to partly overcome this limitation in this paper.

In vivo toxic studies and biodistribution of near infrared sensitive Au-Au(2)S nanoparticles as potential drug delivery carriers.

Near infrared (NIR) sensitive Au-Au(2)S nanoparticles are intensively being developed for biomedical applications including drug and gene delivery. Although all possible clinical applications will require compatibility of Au-Au(2)S nanoparticles with the biological milieu, their in vivo capabilities and limitations have not yet been explored. Au-Au(2)S nanoparticles and cisplatin-loaded Au-Au(2)S nanoparticles were successfully synthesized by the reduction of tetrachloroauric acid (HAuCl(4)) using sodium sulfide (Na(2)S), and cisplatin was loaded onto NIR sensitive Au-Au(2)S nanoparticles via an MUA (11-mercaptoundecanoic acid) layer.

Inhibition of DNA hybridization by small metal nanoparticles.

The inhibition of DNA hybridization by small metal nanoparticles has been examined in detail. DNA melting point analysis showed that the oligonucleotides adsorb strongly and nonspecifically on small metal nanoparticles, inhibiting the hybridization of complementary DNA sequences in common buffered solutions. The nonspecific interaction is even strong enough to disrupt pre-existing hydrogen bonds in short double-stranded DNA.