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We report an unambiguous observation of a room temperature (RT) converse magnetoelectric effect (CME) in ternary BiFeO3-based systems near a morphotropic phase boundary (MPB). The results of in situ XRD diffraction at different applied electric fields reveal that the lattice distortion and phase transitions dominate the RT CME in the samples near the MPB. Our results provide an experimental proof and an explanation for the electric-field control of the magnetism effect obtained at the MPB, which may provide an effective way to design multiferroics for potential applications in magnetoelectric devices with low power consumption.

The high-quality (111)-oriented pyrochlore oxide thin films Y2(Hf1-xIrx)2O7 (YHIO) were prepared by pulsed laser deposition. The bandgap values of Ir-substituted YHIO thin films for x = 0–0.5 range from 4.6 to 1.9 eV. Taking account of spin orbital coupling and correlation effect (U), the first-principles calculations based on density functional theory were used to intercept this variation. The theoretical results illustrate that the variation is attributed to the lower Ir 5d orbital in energy and stronger orbital hybridization between the oxygen 2p orbital and the Ir 5d orbital near the Fermi surface. These results suggest that we can widely modulate the bandgap through B-site chemical substitution based on the Y2Hf2O7 thin film.

Vertically aligned nanostructured (VAN) epitaxial La0.5Ca0.5MnO3 (LCMO) single-phase thin films have been achieved on (LaAlO3)0.3(Sr2AlTaO6)0.7 (001) [LSAT (001)] substrates under high magnetic fields applied in pulsed laser deposition processing. Low-field magnetoresistance (LFMR) in the LCMO VAN films can be effectively manipulated through varying the high magnetic field strength. The tunability of VAN on the electrical transport properties is dependent on control of the high magnetic field on the microstructures, including the geometrical arrangement, vertical interfaces, and vertical grain boundaries (GBs). An LFMR value as high as 45% at 150 K and 1 T has been achieved in an LCMO VAN film grown at 10 T, and its LFMR values are larger than 25% at 127–200 K and 1 T. The tunable and enhanced LFMR in the LCMO VAN films over a wide temperature range can be attributed to the increase in vertical interfaces and GB density with the increasing high magnetic field, which are highly related to the spin-polarized tunneling effect. Applying a high magnetic field in film deposition to control the microstructures of VAN single-phase films is a feasible route to achieve tunable and desirable physical properties.

Flexible Ba2Bi4Ti5O18 and BiFe0.93Mn0.07O3/Ba2Bi4Ti5O18 heterostructure thin-film capacitors were deposited onto LaNiO3 buffered fluorophlogopite mica substrates using a cost-effective all-solution chemical solution deposition method. The Ba2Bi4Ti5O18 film showed a high recoverable energy storage density (Ure) of 41.2 J/cm3 and efficiency (η) of 79.1%. The BiFe0.93Mn0.07O3/Ba2Bi4Ti5O18 film showed improved energy storage properties with an ultrahigh Ure of 52.6 J/cm3 and η of 75.9% due to its enhanced breakdown field strength and polarization. Meanwhile, both films showed good mechanical flexibility, excellent fatigue endurance up to 5 × 108 cycles, and excellent thermal stability over a wide temperature range from room temperature to 160 °C. These results indicate that the lead-free, flexible Ba2Bi4Ti5O18 and BiFe0.93Mn0.07O3/Ba2Bi4Ti5O18 heterostructure thin film capacitors show promise in the field of flexible electronics.

Epitaxial BaSnO3 (BSO) thin films doped with different rare-earth elements (La, Pr, and Nd) were prepared by a simple solution deposition method. Grain size engineering through processing was achieved to tune both lateral and vertical grain sizes, resulting in obvious increments in carrier mobility. Improved performance with the room-temperature mobility exceeding 35 cm2 V−1 s−1 and resistivity as low as 0.55 mΩ cm was realized. The results will open a low-cost route for preparation of large-area BSO thin films with improved optoelectronic properties through the solution method.

Developing lead-free film dielectric capacitors with high-performance of energy storage density, efficiency, fatigue endurance, and thermal stabilities is desirable. Here, we report energy storage properties in (1-x)BaTiO3-xBi3.25La0.75Ti3O12 thin films. It is revealed that a 0.6BaTiO3-0.4Bi3.25La0.75Ti3O12 thin film with a thickness of 280 nm and a crystallization temperature of 650 °C shows a breakdown strength of 3.23 MV/cm with a large polarization value and dielectric constant. An ultrahigh energy storage density of 61.1 J/cm3 and an efficiency of 84.2% are simultaneously achieved at room temperature. Additionally, excellent fatigue endurance after 6 × 109 cycles and good thermal stability up to 150 °C are observed, implying excellent energy storage performance in 0.6BaTiO3-0.4Bi3.25La0.75Ti3O12 thin films.

In this study, hole-type high-temperature superconductor Bi2Sr2CaCu2Oy (Bi-2212) with strong electronic correlation is proposed as a p-type transparent conducting oxide (TCO) candidate. Phase-pure and c-axis oriented Bi-2212 thin films with different thicknesses were prepared to investigate the optoelectronic properties. High room-temperature conductivity between 1064 and 200 S/cm with visible transmittance over 50% is obtained for the prepared Bi-2212 thin films. The results will provide an arena to search for p-type TCOs in high-temperature superconductors with strong electronic correlation and give a potential application in the field of transparent metallic contacts as well as transparent correlated metal/n-type semiconductor Schottky diodes.

Thin film ferroelectric capacitors (TFFCs) with excellent energy storage have attracted increasing attention due to the electronic devices toward miniaturization and integration. BiFeO3 (BF)/Bi3.25La0.75Ti3O12 (BL) based thin films are prepared by chemical solution deposition for energy storage. Ultrahigh energy storage with a recoverable energy density Ure of 54.9 J/cm3 and an efficiency η of 74.4% is observed in the bilayered BF/BL thin films. Further improvement of energy storage is realized in trilayered BL/BF/BL thin films with a Ure of 65.5 J/cm3 and an efficiency η of 74.2% at an electric field of 2753 kV/cm as well as excellent fatigue endurance up to 109 cycles. The results suggest that BF/BL based thin films can be used as lead-free TFFCs in energy storage applications.

Environmentally benign Bi3.25La0.75Ti3O12 (BLTO) thin film capacitors were prepared by a cost effective chemical solution deposition method for high energy density storage device applications. Low annealing temperature annealed BLTO thin films showed very slim hysteresis loops with high maximum and small remnant polarization values. Increasing the applied electric field to 2040 kV/cm, the optimized BLTO thin films show a high recoverable energy density of 44.7 J/cm3 and an energy efficiency of 78.4% at room temperature. Additionally, the BLTO thin film capacitors exhibited excellent fatigue endurance after 4 × 108 cycles and a good thermal stability up to 140 °C, proving their strong potential for high energy density storage and conversion applications.

High room temperature coercivity CoFe2O4 (CFO) thin films are desirable in view of many applications, which is seldom achieved over 3 kOe in solution deposited CFO thin films. Herein, grain growth kinetic is investigated in the solution derived CFO thin films with coercivity larger than 4 kOe, showing a relaxation mechanism. The coercivity and magnetization increase initially and then decrease with increasing dwell time. The high coercivity is originated mainly from the critical grain size and the growth strain induced by the small crystallites and poorly developed grains. The results will provide a route to fabricate larger-area CFO thin films with high coercivity on silicon wafers by low-cost solution processing.

As a type of perovskite transparent conducting oxides, La-doped BaSnO3 is considered as a very important material to construct all transparent perovskite devices. The difficulty in achievement of large-area films with high electrical mobility has hindered the development of La-doped BaSnO3 films. Here, we report the results about chemical solution deposition of Ba0.92La0.08SnO3−δ (BLSO) films. The post-annealing and atmosphere as well as lattice mismatch have been investigated. Post-annealing at 1000 °C can obviously improve the performance due to the enhanced crystallization. Under post-annealing in N2 atmosphere the room-temperature resistivity and electrical mobility can achieve 3.25 mΩ cm and 11.09 cm2 V−1 s−1, respectively, for the BLSO on LaAlO3 single crystal substrates due to the enhanced oxygen deficiencies. BLSO films with different orientation can be easily obtained by selection of the substrates, showing isotropic physical properties. Furthermore, the room-temperature resistivity and mobility ...

We investigated the superconducting transition temperature Tc of FeSe0.5Te0.5 single crystals, which can be enhanced up to 14% by attaching onto a commercial Scotch tape. The Scotch tape exhibits a large cooling shrinkage at low temperatures, which is considerably more pronounced than that of the metallic FeSe0.5Te0.5 single crystal, thus providing a compressive strain of 2.4 × 10−3 at 15 K. For such strain, we calculated that the lattice parameter of c/a can be increased to ∼0.31%, which corresponds to the enhancement of the superconductivity. The present finding provides a rapid and simple method to examine the microstructure sensitive physical properties of the layered-structure materials by using the Scotch tape as strain generator.