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Perovskite semiconductors, as an emerging material, have gained widespread attention in the preparation of memristor devices with resistive switching (RS) behavior due to their excellent properties, such as ion migration, adjustable bandgap, and high OFF/ON ratio. The negative differential resistance (NDR) effect-coupled RS behavior has important prospects for the preparation of multifunctional devices due to its potential to break the limitations of Moore's law. In this work, the La0.7Sr0.3MnO3 films with different nanoscale thicknesses were prepared on fluorine-doped SnO2 (FTO) substrates by the radio frequency (RF) magnetron sputtering method as a functional layer of the memristor device. The Ag/La0.7Sr0.3MnO3/FTO memristor device achieves bipolar RS behavior with both nonvolatile memory and NDR effect, and the NDR-coupled RS effect can be successfully regulated by the functional layer thickness and bias voltage range. The conduction mechanism of the NDR-coupled RS phenomenon in the device can be explained by the formation and fracture of metal ion oxygen vacancy (V02+) conduction paths inside the functional layer. This work provides an important avenue for understanding the multiple physical mechanisms in memristor devices. [ABSTRACT FROM AUTHOR]

In this work, the enhancement of the magnetocaloric effect by mixing different alkaline-earth-doped lanthanum manganites is reported. The sintering process of the mixed manganites promotes the unexpected presence of a strontium–calcium-co-doped lanthanum manganite phase that enhances the magnetocaloric properties of the composite. Consistent with this result, the composite shows three Curie temperatures at 263 K, 309 K, and 284 K, attributed to the three different phases found. The transition was identified as a second-order phase transition by the Arrott plots. A maximum entropy change of 11.66 J·(kg·K)−1 was obtained for the composite at 18 kOe. It corresponds to a refrigeration cooling power of 484.98 J·kg−1 near room temperature. The results demonstrated the synergistic contribution to the magnetocaloric properties of individual phases, enhancing the magnetocaloric effect by obtaining a composite. [ABSTRACT FROM AUTHOR]

The possibility to fabricate freestanding single crystal complex oxide films has raised enormous interest to be integrated in next‐generation electronic devices envisaging distinct and novel properties that can deliver unprecedented performance improvement compared to traditional semiconductors. The use of the water‐soluble Sr3Al2O6 (SAO) sacrificial layer to detach the complex oxide film from the growth substrate has significantly expanded the complex oxide perovskite membranes library. Nonetheless, the extreme water sensitivity of SAO hinders its manipulation in ambient conditions and restricts the deposition approaches to those using high vacuum. This study presents a pioneering study on the role of Ca‐substitution in solution processed SAO (Sr3−xCaxAl2O6 with x ⩽ 3) identifying a noticeable improvement on surface film crystallinity preserving a smooth surface morphology while favoring the manipulation in a less‐restricted ambient conditions. Then, the study focuses on the effect of the sacrificial composition on the subsequent ex situ deposition of La0.7Sr0.3MnO3 (LSMO) by pulsed laser deposition, to obtain epitaxial films with a variable degree of strain. Finally, epitaxial and strain‐free LSMO membranes with metal‐insulator transition at 290 K are delivered. This study offers a hybrid and versatile approach to prepare and easily manipulate crystalline perovskite oxide membranes by facilitating ex situ growth on SAO‐based sacrificial layer. [ABSTRACT FROM AUTHOR]

In this work bilayer structures, composed of ferromagnetic manganite and ferroelectric titanate layers, were obtained by solution deposition technique. The first step in preparation of the bilayer thin films was deposition of manganite (LaMnO3 or La0.7Sr0.3MnO3) layer by water-based polymer assisted deposition (PAD). Polycrystalline structures were obtained when manganite films were deposited by spin coating on commercial Pt/TiO2/SiO2/Si type substrate, whereas epitaxial films were grown on a single crystal SrTiO3 with (001) orientation substrate. The second ferroelectric titanate (BaTiO3 or Ba0.7Sr0.3TiO3) layer was deposited by spin coating using sol-gel method. The obtained bilayer structures have thickness below 100 nm, and epitaxial growth of the Ba0.7Sr0.3TiO3 film on the La0.7Sr0.3MnO3 surface was obtained, due to the similar lattice parameters between these two crystal structures.

In this work, we simulated the dependence of magnetization versus temperature for highly (001)-oriented La0.7Sr0.3MnO3 (LSM) thin film prepared under several oxygen growth pressures to predict magnetocaloric effect (MCE). The results reveal that MCE of highly (001)-oriented LSM thin films is strongly tunable with oxygen growth pressure during preparation. Furthermore, the MCE of these films is enhanced with increasing oxygen growth pressure during preparation. The comparison of MCE parameters for (001)-oriented LSM thin films and some published works has been done, showing that these films are considerably larger and comparable with some MCE parameters of these published works. It is suggested that (001)-oriented LSM thin films can be used as a function material of MR that cools at cryogenic and room temperatures.

Polycrystalline La0.7Sr0.3MnO3 sample (LSMO) was synthesized by the solid phase reaction; it exhibits the paramagnetic‐ferromagnetic transition at Tc = 362 K at the ambient pressure; it is paramagnetic metallic state above Tc and the ferromagnetic metallic state below Tc. It was observed that the pressure effect depends on the temperature range: (a) In the paramagnetic region, the magnetization M hardly changes with the pressure P, that is, ΔM≈0. There exist the antiferromagnetic (AFM) coupled ferromagnetic clusters in the paramagnetic region, and the pressure enhances the AFM coupling. (b) In the temperature range around Tc, the pressure increases M, that is, ΔM > 0, with the concomitant increase in Tc; the average pressure coefficient dTc/dP is 5.40 K/GPa at P =.74 GPa, much smaller than 15.47 and 15.90 K/GPa for La0.7Ca0.3MnO3 and La0.9Ca0.1MnO3, respectively, due to the different distortion degree of MnO6 octahedra in Ca and Sr doped manganites. (c) In the temperature region below Tc, the pressure reduces M, that is, ΔM < 0. M is determined by the competition between the Mn3+‐O‐Mn4+ double exchange and the interparticle dipolar interaction. The pressure enhances the interparticle dipolar interaction, leading to a significant decrease in magnetization. The resistivity of LSMO exhibits the metallic behavior in the temperature range of 5 K~370 K; it decreases as the applied magnetic field H increases from 0 to 7 T, that is, the magnetoresistance effect which is more significant around Tc. The fitting to the low‐temperature resistivity shows that the applied magnetic field reduces the scattering from the grain boundary, electron, phonon, and magnon, especially reduces the electron‐electron scattering. [ABSTRACT FROM AUTHOR]

Self-assembled epitaxial La0.7Sr0.3MnO3:NiO (LSMO:NiO) nanocomposite thin films were grown on (001)-oriented SrTiO3 substrates by pulsed laser deposition, and their microstructures and magnetoresistance (MR) properties were investigated. The room temperature MR effect at a low magnetic field has been realized in the composite films, and the maximum MR value is 18.7% at 300 K and 1 T. The room temperature MR properties at the low magnetic field can be attributed to the special structure, which is made up of the nano-sized LSMO and NiO columns. The room temperature MR properties at low magnetic fields will facilitate its extensive room temperature applications.

Through a simple and low-cost way to gain the precursor solution, a conductive and high-quality La0.7Sr0.3MnO3 (LSMO) buffer layer approximately 280 nm thick only by one single coating was successfully deposited on LaAlO3 (LAO) (100) single crystal substrates using an independently developed new method of polymer-assisted chemical solution deposition (PA-CSD). Highly epitaxial YBa2Cu3O7−x (YBCO) superconducting film with thickness of 500 nm managed to be deposited on LSMO/LAO. A study was made on the LSMO buffers and YBCO films with XRD, SEM, and superconducting critical temperature (Tc) analyses. The temperature-dependent resistivities of YBCO on insulating BaZrO3 (BZO) buffer layer and on conductive LSMO buffer layer were also investigated. It was found that the conductive LSMO buffer prepared at 840 °C in argon would possess high-degree out-of-plane and in-plane texturing, good density with a sufficient thickness about 280 nm, and microcrack-free nature. More importantly, the value of the self-field critical current density (Jc) of YBCO superconducting film on LSMO/LAO architecture was 2.8 MA/cm2 at 77 K. [ABSTRACT FROM AUTHOR]

Magnetization enhancement is observed in the bi-magnetic systems including paramagnetic (PM)/antiferromagnetic (AFM), AFM/AFM, and ferromagnetic (FM)/AFM composites systems, and attributed to the effects of oxidation states of metallic ions on the interface exchange-coupling. With respect to the FM/FM system, in this study, the enhanced magnetization in hard CoFe 2 O 4 (CFO)/soft La 0.7 Sr 0.3 MnO 3 (LSMO) composites with different mass ratios of LSMO (R s) was observed for the first time. The values of saturation magnetization (M s) of CFO and LSMO at 10 K were found to be 111 and 113 emu/g, respectively. For the CFO/LSMO composites, M s was below 111 emu/g for R s ≤ 15% because the antiferromagnetically coupled CFO/LSMO system maintains the super-spin glass (SSG) state with the moment of CFO particles being randomly oriented. However, M s increases to 133 and 127 emu/g for R s = 18 and 21%, respectively, because the higher content of LSMO separates the CFO particles and destroys the SSG state, thus enabling the moment of CFO particles to rotate easily and align with the external magnetic field. Mechanism for the magnetization enhancement reported herein is different from the interface exchange-coupling mechanism, which enriches the understanding of the magnetization reversal in bi-magnetic systems and provides the experimental reference for the applications of bi-magnetic materials. [ABSTRACT FROM AUTHOR]

Characterization of the onset of a phase transition is often challenging due to the fluctuations of the correlation length scales of the order parameters. This is especially true for second-order structuralphase transition due to minute changes involved in the relevant lattice constants. A classic example is the cubic-to-tetragonal secondorder phase transition in SrTiO3 (STO), which is so subtle that it is still unresolved. Here, we demonstrate an approach to resolve this issue by epitaxially grown rhombohedral La0.7Sr0.3MnO3 (LSMO) thin films on the cubic STO (100) substrate. The shear strain induced nanotwinning waves in the LSMO film are extremely sensitive to the cubic-totetragonal structural-phase transitions of the STO substrate. Upon cooling from room temperature, the development of the nanotwinning waves is spatially inhomogeneous. Untwinned, atomically flat domains, ranging in size from 100 to 300 nm, start to appear randomly in the twinned phase between 265 and 175 K. At ~139 K, the untwinned, atomically flat domains start to grow rapidly into micrometer scale and finally become dominant at ~108 K. These results indicate that the low-temperature tetragonal precursor phase of STO has already nucleated at 265 K, significantly higher than the critical temperature of STO (~105 K). Our work paves a pathway to visualize the onset stages of structural-phase transitions that are too subtle to be observed using direct-imaging methods. [ABSTRACT FROM AUTHOR]

We observe large room-temperature magnetodielectric effect (nearly 12% suppression of dielectric constant under ∼ 20 kOe field) as well as its remarkable field-driven switch – from positive to negative – in polyvinylidene fluoride-trifluoroethylene/La 0.7 Sr 0.3 MnO 3 (PVDF-TrFE/LSMO) thin films (0–3 connectivity) containing 7.5 volume% LSMO. The magnetodielectric effect is mapped with the volume fraction of the LSMO nanoparticle across 5-20 volume%. It reveals a close correlation among the LSMO nanoparticles volume fraction, their distribution pattern within the PVDF-TrFE matrix, uniformity in the magnetic domain size (imaged by magnetic force microscopy), and the magnetodielectric effect. The observed 20% jump in the intrinsic bulk capacitance at a critical magnetic field H C ∼ 10 kOe can be exploited to develop smart nanoscale magnetoelectric devices. • Magnetodielectric effect is influenced by LSMO particle distribution within PVDF • Sample with ∼ 7.5 vol% LSMO particles yields maximum magnetodielectric effect • Uniform magnetic field is generated within the sample with ∼ 7.5 vol% LSMO particles • Magnetodielectric effect switches from positive to negative at ∼ 10 kOe. [ABSTRACT FROM AUTHOR]

Self-assembled epitaxial La0.7Sr0.3MnO3:NiO (LSMO:NiO) nanocomposite thin films were grown on (001)-oriented SrTiO3 substrates by pulsed laser deposition, and their microstructures and magnetoresistance (MR) properties were investigated. The room temperature MR effect at a low magnetic field has been realized in the composite films, and the maximum MR value is 18.7% at 300 K and 1 T. The room temperature MR properties at the low magnetic field can be attributed to the special structure, which is made up of the nano-sized LSMO and NiO columns. The room temperature MR properties at low magnetic fields will facilitate its extensive room temperature applications. IMPACT STATEMENT The room temperature magnetoresistance properties at a low magnetic field has been realized in the self-assembled epitaxial La0.7Sr0.3MnO3:NiO nanocomposite thin films by controlling the microstructures. [ABSTRACT FROM AUTHOR]

Artificially constructed oxide heterointerfaces have attracted much attention. Herein, the novel all-perovskite p-n heterojunction composed of a colossal magnetoresistive manganite La0.7Sr0.3 MnO3 (LSMO) and an n-type transparent semiconducting BaSnO3 (BSO) is designed via optimizing the growth condition. This LSMO/BSO p-n junction exhibits good rectification with a forward-to-reverse ratio of 275 at 1 V, high photo detection capability with a photo-to-dark current of 581.9 at -0.5 V, high ultraviolet light sensitivity with a UV (360 nm)-to-visible (532 nm) ratio of ∼2.4 × 103, and a significantly magneto-tunable photocurrent with a variation ratio of ∼1.25 % under 532 nm illumination and 0.5 T magnetic field. As a result, combining synergistically the functionality of diode and magnetically tunable photo detector, the LSMO/BSO p-n junction is a promising candidate for advanced magneto-optoelectronic devices. [ABSTRACT FROM AUTHOR]

Interaction of conduction electrons with non-coplanar or non-collinear spin textures in metals can result in intriguing phenomena, among which a topological Hall effect. Here, we report on topological Hall effect manifestation in epitaxial heterostructures of thin metallic layers of two prototypical ferromagnetic oxides, namely [ABSTRACT FROM AUTHOR]

La0.7Sr0.3MnO3/SrTiO3/La0.7Sr0.3MnO3 magnetic tunnel junction was grown on (001)-oriented Sr-TiO3 substrate by using pulsed laser deposition technique. La0.7Sr0.3MnO3 (LSMO) was used as ferromagnetic (FM) electrodes and SrTiO3 (STO) was used as a tunnel barrier. The effect of temperature and magnetic field on electrical transport properties has been investigated. Bottom electrode and junction resistances were observed to strongly depend on temperature. Large magnetoresistance of almost 300% was observed at 77.3 K at low magnetic fields of a few tens of Oe. The large magnetoresistance was explained by the nearly half-metallic band structure of La0.7Sr0.3MnO3. The asymmetry of TMR curves was attributed to the ferromagnetic electrodes with different thickness and the differences in the electronic states of the upper and lower STO/LSMO interfaces. [ABSTRACT FROM AUTHOR]

• Epitaxial strain strongly influences the resistance of the La 0.7 Sr 0.3 MnO 3 thin film. • The thin film under a compressive strain has lower oxygen vacancy formation energy. • Ionic liquid-gated method reversibly controls the properties of compressed thin film. Reversible manipulation of magnetic and electric transport properties by electrical means in perovskite transition metal oxides is of paramount importance in modern condensed matter physics and generates promising application prospects in electronic devices. However, the conventional method of field-effect transistor structure presents a huge limitation due to its poor ability to modulate the exceedingly high carrier density of about 1014−1015 cm−2. In this study, La 0.7 Sr 0.3 MnO 3 (LSMO) epitaxial thin films with tensile and compressive strain states were obtained by growth on different single-crystal substrates. Compared with the LSMO thin film under tensile strain, the compressed LSMO thin film possesses more oxygen vacancies, a higher resistance and a smaller magnetization. In addition, the structural phases, magnetic and electric transport properties in both LSMO thin films were also manipulated by the ionic liquid-gated method. The LSMO thin film under compressive strain shows easier access to the reversible control of the structural phase and magnetic & electrical transport properties than the LSMO thin film under tensile strain. The synergy of the above capabilities proves an effective and reversible route to manipulate the properties of perovskite transition metal oxides, providing tremendous potential in the design of multiple-state memories, neuromorphic transistors, and other multifunctional devices. [ABSTRACT FROM AUTHOR]

The LSMO films were prepared on Si substrates by chemical solution deposition method. The films were annealing in air and O2atmosphere. All films have perfectly crystallized. Compared with the LSMO films annealing in air, the residual and saturation magnetic moment value were much lower for the films annealing in O2. The Tcof the LSMO films annealing in O2is higher about 15 K than that annealing in air. The variation of magnetization and Tc with annealing in O2is thus consistent with the change of Sr content and is almost certainly related to the Mn3+/Mn4+ratio. The MR value is decreased with the increasing temperature. It is observed that the transport properties, both the resistivity and the magnetoresistance value, have similar variation behavior. It is because that the La(Sr) vacancies (δ > 0) are expected to have indirect perturb the conduction path. The resistivity and the MR value at 7 T of the both films are (0.145 Ω.cm, 59.3%), (0.208 Ω.cm, 60.0%), respectively. [ABSTRACT FROM AUTHOR]

The core/shell structural MFe2O4/La0.7Sr0.3MnO3(M=Ni,Co,Zn) magnetic nanocomposites particles were prepared by a polyacrylamide Sol-Gel method, analytically pure nitrate as the main materials. The XRD, SEM, TEM, EDS and VSM were used to analyze the chemical component, structure, morphology and magnetic property of the nanocomposites. The result show that the pH value of the solution was adjusted to 3, the mass ratio of core/shellwas 1:2, the dry gel was heated at 500°C for 10h, and then 600°C for 6h can obtain core/shell structural nanocomposites with particle size uniform and scattered homogeneously. We find out the composition and structure of nanocomposites have great influence on their magnetic property. [ABSTRACT FROM PUBLISHER]

Magnetic properties and low-field magnetoresistance (LFMR) in La0.7Sr0.3MnO3 (LSMO):NiO nanocomposite films grown on SrTiO3 (001) substrates, which are shown to be tunable with different microstructures, are investigated. The LSMO:NiO nanocomposite films with NiO volume ratio of 50% have a checkerboard-like structure and show a large LFMR in a temperature range from 200 to 300 K (≈17% at 250 K with a magnetic field of 1 T). As the NiO volume ratio is increased to 70%, a nano-columnar structure formed in the films. Their LFMR is significantly enhanced at a wide temperature range of 10-210 K. The highest value of LFMR with 41% is achieved at 10 K in a magnetic field of 1 T. The enhanced LFMR can be considered to result from the electron scattering at the ferromagnetic LSMO/NiO interfaces and magnetic tunnel junctions (MTJs) of LSMO/NiO/LSMO at the nanometer scale. These results demonstrate that large and tunable LFMR from low temperature to room temperature can be realized by controlling the microstructures in the epitaxial La0.7Sr0.3MnO3:NiO nano­composite thin films, which will be expected to be applied in the devices using for a wide temperature range. [ABSTRACT FROM AUTHOR]

Sol–gel and dip-coating technologies have been used to deposit La0.7Sr0.3MnO3 (LSM) porous thin films on stainless steel SS444-Cr-17% interconnect plates. Single and double LSM layers were fired in air at 800 °C for 2 h to achieve a sufficient adhesion on the substrate. The microstructure and composition of oxide scales were investigated using X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. The area specific resistance (ASR) for coated and uncoated plates was evaluated during long term oxidation in air at 800 °C for 200 h, and between 600 and 900 °C, by DC two point measurements. The formation of an interfacial oxide scale based on (Cr,Mn)3O4 spinel and Cr2O3 has been evidenced for uncoated and LSM-coated SS444. The results indicate that the oxidation resistance of the alloy is enhanced by a protective coating consisting of one single LSM layer. ASR values as low as 0.6 mΩ cm2 were recorded after 200 h at 800 °C. The effectiveness of the LSM layer as a protective coating depends on the stability of the film and its adherence on the alloy substrate. [ABSTRACT FROM AUTHOR]

Abstract: Ferroelectric BaTiO3 (BTO) as well as ferromagnetic La0.7Sr0.3MnO3 (LSMO) thin films were prepared by chemical solution deposition (CSD). Based on these, a multiferroic architecture stack of La0.7Sr0.3MnO3/BaTiO3 layers was developed. Aqueous, environment friendly precursor solutions were formulated for both materials. These are used for ink plotting on SrTiO3 (100) substrates. Films were subjected to a subsequent thermal treatment at the corresponding crystallization temperature. The structural as well as the magnetic and electric properties are presented. The Curie temperature of the ferromagnetic LSMO layer with a film thickness of only 60nm was determined to 360K. The magnetization curve indicates a hysteresis loop with a saturation magnetization above 400emu/cm3. The ferroelectric character of the BTO films was demonstrated by polarization curves. [Copyright &y& Elsevier]

Abstract: Nanoscale structuring on La0.7Sr0.3MnO3 (LSMO) thin film surfaces has been performed by scanning tunneling microscopy (STM) under ambient conditions. From line etching experiments we found that the line-depth increases in a stepwise fashion with increasing bias voltage. It also increases with decreasing scan speed and increasing scan repetition. We observed that the line-depth is an integral multiple of the LSMO out-of-plane lattice constant about 0.4nm. Lateral structure with minimum feature size of 1nm is possible to obtain. In addition, a four-level inverse-pyramid structure has been created on LSMO thin film surfaces. Our work shows the feasibility of using STM to fabricate controllable and complex nanostructures in LSMO thin film. [ABSTRACT FROM AUTHOR]

Abstract: The transport properties of the samples La0.7Sr0.3Mn1− x Ti x O3 were investigated using admittance spectroscopy. In contrary to free compound, when titanium is introduced, the conductance becomes frequency and temperature dependent. From DC conductance study, electronic conduction is found to be dominated by thermally activated hopping and depending strongly on Ti content. Activation energy is deduced from the variation of conductance with temperature. This energy decreases from 168 to 143meV when x increases from 0.05 to 0.20. The AC conductance spectrum is found to obey Jonscher universal power law. Finally, at ambient temperature, DC conductance decreases with the value of x and proves a clear effect of titanium in transport properties of the material. This decrease of conductance is explained by a reduction of Mn3+–O–Mn4+ network responsible for electrical conduction in perovskite. [Copyright &y& Elsevier]

• Robust, reversible switching were observed in CuI-La 0.7 Sr 0.3 MnO 3 nanocomposites. • CuI and La 0.7 Sr 0.3 MnO 3 individually didn't show switching but nanocomposites did. • The pattern of hysteretic pulse IV plot didn't vary drastically over repeated cycles. • Schottky emission and Poole–Frenkel effect were the dominant transport mechanisms. • Resistive switching was stable over 1000 cycles of square pulse train measurement. In this study, we reported the presence of robust, reversible unipolar electric pulse-induced resistance switching effects in copper iodide and La 0.7 Sr 0.3 MnO 3 nanocomposites. The properties of the resistive switching and change in the I–V pattern was analyzed over 100 cycles by hysteretic pulse current–voltage measurement (pulse width = 0.01 s and pulse period = 0.02 s). The charge transport analysis of various regions of the 1st cycle pointed towards Schottky emission and Poole–Frenkel effect to be the dominant mechanisms in lower bias region and higher bias region respectively. On the other hand, resistive switching turned out to be stable over 1000 cycles of square electrical pulse train measurement where frequency of 125 Hz (pulse period 2 ms and pulse width 100 μ s) and 250 Hz (pulse period 1 ms and pulse width 50 μ s) were used. [ABSTRACT FROM AUTHOR]

Abstract: The electrochemical performance of anode-supported single-chamber solid oxide fuel cells (SC-SOFCs) with and without SDC-impregnated cathodes was compared in a diluted methane–oxygen mixture. These cells were made of conventional materials including yttrium-stabilized zirconia (YSZ) thin film, a Ni+YSZ anode and a La0.7Sr0.3MnO3 (LSM) cathode. Our results showed that the cell performance was greatly enhanced with the SDC-impregnated LSM cathode. At a furnace temperature of 750°C, the maximum power density was as high as 404mWcm−2 for a CH4 to O2 ratio of 2:1, which was 4.0 times higher than the cell with a pure LSM cathode (100mWcm−2). The overall polarization resistance of the impregnated cell was 1.6Ωcm2, which was much smaller than that of the non-impregnated one (4.2Ωcm2). The impregnation introduced SDC nanoparticles greatly extended the electrochemical active zone and hence greatly improved the cell performance. [Copyright &y& Elsevier]

Abstract: The microstructures of Ba0.7Sr0.3TiO3/La0.7Sr0.3MnO3 (BST/LSMO) thin films epitaxially grown on (001) LaAlO3 substrate by pulsed laser deposition were investigated by transmission electron microscopy (TEM) and related techniques. Both cross-sectional and plan-view TEM specimens were studied. The predominant defects in the films are a high density of threading dislocations (TDs) perpendicular or quasi-perpendicular to the substrate surface. Diffraction contrast and high-resolution transmission electron microscopy (HRTEM) techniques reveal that the TDs are mostly pure-edge-type with Burgers vectors b =<100> or <110>. There are a few TDs of screw character, and convergent beam electron diffraction (CBED) analysis shows the screw component of their Burgers vectors is ±[001]. The formation mechanisms of the TDs are discussed. [Copyright &y& Elsevier]

Abstract: Using RF magnetron sputtering, we have successfully grown (110) orientated La0.7Sr0.3MnO3 (LSMO) films on Si(001) wafers using SrMnO3 (SMO) as a template layer. The X-ray diffraction (XRD) patterns of the SMO/Si heterostructures indicate that SMO grows along the (110) orientation, the orientation relationship between the SMO thin film and the Si (001) substrate being given by (011)SMO∣∣(001)Si and [01]SMO∣∣[010]Si. From the XRD patterns of the LSMO/SMO/Si heterostructures, we find that with an increase of substrate temperature, the required thickness of SMO, which plays an effective role of tuning the preferential orientation of LSMO, will decrease at first and then increase. It is thought that this originates from the fact that the crystallization of SMO is not perfect at low temperatures whereas too high a temperature results in reaction and diffusion at the interface of the two layers. [Copyright &y& Elsevier]

La0.7Sr0.3MnO3 (LSMO) films of variable thickness were deposited by magnetron sputtering on a LaAlO3(1 0 0) substrate. The substrate–film lattice mismatch causes changes in the microstructure and magnetoresistance. The film structure is characterized by XRD. The substrate–film lattice mismatch is compensated by large stress in the LSMO layer at interface. With increasing film thickness this stress relaxes and the upper film layer exhibits bulk value lattice parameters. It was shown that deposition conditions also influence film stress. Due to variable strain in the thin LSMO films, different magnetoresistive behaviour has been found. The sample with the lowest thickness of 10 nm showed semiconducting behaviour. Epitaxial LSMO films of thickness 20 nmTC∼365 K and colossal magnetoresistance behaviour. A highly stressed film with a metal–insulator transition at ∼160 K showed both high negative magnetoresistance at T=150 K and marked high positive magnetoresistance at T<50 K. [Copyright &y& Elsevier]

Thin films of La0.7Sr0.3MnO3 were deposited by magnetron sputtering on SrTiO3(1 0 0) and LaAlO3(1 0 0) substrates. The influence of deposition parameters such as substrate temperature, chamber pressure as well as film growth rate on structural and magnetic properties was investigated. The structural characterisation by means of X-ray diffraction (θ/2θ scans, ω-scans, ϕ-scans) revealed high quality of the epitaxial LSMO films obtained at a growth rate of 2 nm/min with a small mosaicity in the plane of the substrate. By optimisation of the deposition regime, especially by decreasing the film growth rate down to 0.77–1.6 nm/min and increasing the substrate temperature up to 840°C, a further improvement of the film epitaxy as well as magnetic properties has been registered by RBS and SQUID measurements. Improved epitaxy leads to a decrease of LSMO resistivity down to values ∼100 μΩ cm comparable with those of the best-quality LSMO films. The magnetoresistance MR=[R(H)−R(0)]/R(0) of the films obtained is low at low temperature due to structural perfection. However, epitaxial strain appearing in thinner layers leads to increasing of the magnetoresistance in spite of high structural perfection. Thin LSMO films obtained by magnetron sputtering are appropriate for applications in tunnel structures and multilayers. [Copyright &y& Elsevier]

In this study, PLD growth of La0.7Sr0.3MnO3 (LSMO) tilted nanocolumn boundaries and their magnetoresistance (MR) properties at 77 K were examined. All LSMO films were grown on polycrystalline MgO substrates and step-edged (1 0 0) GaAs substrates (step-edge angles ranged from 0° to 100°) by Ar–F excimer laser ablation (pulsed laser deposition) method. Grains were made up in the shape of the nanocolumns standing normal to the substrates surfaces. The intergrain magnetoresistances (IMRs) showed marked reduction against the magnetic field application below 100 mT, followed by a gradual change for further increase in the field. They clearly showed the nanocolumn boundary angle dependence in accordance with the extended Julliere’s model. [Copyright &y& Elsevier]

La 0.7 Sr 0.3 MnO 3 (LSMO) is one of the most fascinating strongly correlated oxides in which the spin polarization and magnetic property are sensitive to strain, especially in the (111)-oriented LSMO. In the paper, epitaxial LSMO(111) thin films with different thicknesses were prepared, and they showed continuous dislocation defect arrays with thickness greater than 45 nm. Then, the thick LSMO(111) films were divided into a double-layer structure with two slightly different oriented cells. The LSMO(111) films present a stronger lattice-spin coupling, thus the double-layer structure triggers an obvious magnetic heterogeneity phenomenon (magnetic bi-states) by the way of creating a double-mode ferromagnetic resonance (FMR) spectrum. Therefore, the nanostructures, especially the ordered structure defects, may trigger enriched physical phenomena and offer new forms of spin coupling and device functionality in strain-sensitive strongly correlated oxide systems.

The realization of a large low-field magnetoresistance (LFMR) effect in free-standing magnetic oxide films is a crucial goal toward promoting the development of flexible, low power consumption, and nonvolatile memory devices for information storage. La 0.7 Sr 0.3 MnO 3 (LSMO) is an ideal material for spintronic devices due to its excellent magnetic and electronic properties. However, it is difficult to achieve both a large LFMR effect and high flexibility in LSMO films due to the lack of research on LFMR-related mechanisms and the strict LSMO growth conditions, which require rigid substrates. Here, we induced a large LFMR effect in an LSMO/mica heterostructure by utilizing a disorder-related spin-polarized tunneling effect and developed a simple transfer method to obtain free-standing LSMO films for the first time. Electrical and magnetic characterizations of these free-standing LSMO films revealed that all of the principal properties of LSMO were sustained under compressive and tensile conditions. Notably, the magnetoresistance of the processed LSMO film reached up to 16% under an ultrasmall magnetic field (0.1 T), which is 80 times that of a traditional LSMO film. As a demonstration, a stable nonvolatile multivalue storage function in flexible LSMO films was successfully achieved. Our work may pave the way for future wearable resistive memory device applications.

Abstract: La0.7Sr0.3MnO3 powders were fabricated by the traditional solid state reaction at different temperatures. The crystal structure, infrared transmittance spectra, resistivity and infrared normal emissivity ɛ N in the range of 8–14μm were examined using different methods. Effects of sintering temperatures on the infrared emissivity were investigated. It is found that the emissivity of La0.7Sr0.3MnO3 powders decreased first and increased then with the sintering temperature''s increase from 1273K to 1523K, and the lowest infrared emissivity was obtained when calcined at 1473K. The trend of the variation of the infrared normal emissivity with sintering temperature''s increase was opposite to that of crystallite size and similar to that of resistivity. [Copyright &y& Elsevier]

Characterization of the onset of a phase transition is often challenging due to the fluctuations of the correlation length scales of the order parameters. This is especially true for second-order structural-phase transition due to minute changes involved in the relevant lattice constants. A classic example is the cubic-to-tetragonal second-order phase transition in SrTiO 3 (STO), which is so subtle that it is still unresolved. Here, we demonstrate an approach to resolve this issue by epitaxially grown rhombohedral La 0.7 Sr 0.3 MnO 3 (LSMO) thin films on the cubic STO (100) substrate. The shear strain induced nanotwinning waves in the LSMO film are extremely sensitive to the cubic-to-tetragonal structural-phase transitions of the STO substrate. Upon cooling from room temperature, the development of the nanotwinning waves is spatially inhomogeneous. Untwinned, atomically flat domains, ranging in size from 100 to 300 nm, start to appear randomly in the twinned phase between 265 and 175 K. At ∼139 K, the untwinned, atomically flat domains start to grow rapidly into micrometer scale and finally become dominant at ∼108 K. These results indicate that the low-temperature tetragonal precursor phase of STO has already nucleated at 265 K, significantly higher than the critical temperature of STO (∼105 K). Our work paves a pathway to visualize the onset stages of structural-phase transitions that are too subtle to be observed using direct-imaging methods., Competing Interests: The authors declare no conflict of interest.