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The three-dimensional (3D) nanosized compactness of devices is in high demand for the spintronic-device applicability. However, very few self-organized, periodic magnetic 3D nanostructures of transition metal oxides are known. Here, we report the direct microscopic evidence of a self-assembled, square-shaped, periodic array of coherent orthogonal nanoblock-type structure in an epitaxial SrRuO3 (SRO) thin film (∼90 nm thickness) grown on (001) LaAlO3 (LAO) using pulsed-laser deposition technique. The evolution of different growth facets of SRO over the LAO single crystalline substrate with different thickness are observed. The combined effect of substrate-induced strain and misfit is utilized to grow such self-assembled, ordered nanostructure. The spontaneous formation of such ordered ferromagnetic nano-devices can fill the gap of a miniaturized spintronic device for magnetic memory-based applications. [ABSTRACT FROM AUTHOR]

Ferromagnetic insulators (FMIs) have widespread applications in microwave devices, magnetic tunneling junctions, and dissipationless electronic and quantum-spintronic devices. However, the sparsity of the available high-temperature FMIs has led to the quest for a robust and controllable insulating ferromagnetic state. Here, we present compelling evidence of modulation of the magnetic ground state in a SrCoO2.5 (SCO) thin film via strain engineering. The SCO system is an antiferromagnetic insulator with a Neel temperature, TN, of ∼550 K. Applying in-plane compressive strain, the SCO thin film reveals an insulating ferromagnetic state with an extraordinarily high Curie temperature, TC, of ∼750 K. The emerged ferromagnetic state is associated with charge-disproportionation (CD) and spin-state-disproportionation (SSD), involving high-spin Co2+ and low-spin Co4+ ions. The density functional theory calculation also produces an insulating ferromagnetic state in the strained SCO system, consistent with the CD and SSD, which is associated with the structural ordering in the system. Transpiring the insulating ferromagnetic state through modulating the electronic correlation parameters via strain engineering in the SCO thin film will have a significant impact in large areas of modern electronic and spintronic applications. [ABSTRACT FROM AUTHOR]

The study of magneto-optical (MO) properties is reported in epitaxial cerium (Ce) substituted yttrium iron garnet thin films deposited on Gd 3 Ga 5 O 12 (GGG) substrates using pulsed laser deposition technique at (i) different O 2 partial pressure (OPP) during film deposition and (ii) with different film thickness at a given OPP. The MO activity is estimated by measuring the Kerr rotation using the longitudinal magneto-optical Kerr effect with blue (405 nm), green (532 nm), and red (632 nm) incident laser light. The Kerr rotation is observed to increase with an increase in OPP and vary differently with thickness for a given OPP as a function of incident light wavelength. The results are explained in terms of the possible charge transfer mechanism for the films prepared with OPP variation and the optical interference effects in dielectric films with thickness variation. [ABSTRACT FROM AUTHOR]

Control over the movements of free charge carriers across any manganite based interface can functionalize the device for spintronic applications. This can be achieved through external stimuli that alter various electronic phases of manganites having comparable energy levels. In the present communication, the LaMnO3/La0.7Ca0.3MnO3/LaAlO3 (LMO/LCMO/LAO) manganite–manganite structure was successfully fabricated using a cost effective chemical solution deposition (CSD) method. Field effect configuration was employed to understand the interface resistive nature of the LMO/LCMO interface for which externally applied interface electric fields have been applied across the same interface. The applied interface electric field considerably affects the LMO/LCMO interface resistivity which has been discussed in the context of free charge carrier movements across the same interface. The state of the spin fluctuations across manganite lattices has been recognized by fitting the resistivity behavior theoretically using the Zener double exchange (ZDE) polynomial law. Complex electroresistance (ER) and anisotropic magnetoresistance (AMR) behaviors have been discussed in detail for understanding the electrical nature of the LMO/LCMO interface under different applied stimuli. [ABSTRACT FROM AUTHOR]

Carbon ion implantation mediated blue photoluminescence (PL) and the corresponding bluish white phosphorescence of anodic aluminum oxide (AAO) are presented. In particular, the observed 465 nm luminescence is found to be more sensitive to carbon, while its lifetime is raised to its maximum from 6.7 to 10.4 μs at a fluence of 1 × 1016 ions/cm2. The observed phenomenon seems to be associated with the formation of oxygen vacancy (V0) via carbon ion enhanced modification of local AlO6 octahedral symmetry, as revealed from X-ray absorption spectroscopy at O-K edge, and also consistent with X-ray photoelectron spectroscopy (XPS). Detailed XPS analysis indicates the preference of carbon at the Al sites, rather than at O for both octahedral and tetrahedral structures, and form CAl cationic impurity, consistent with our density functional theory calculation. Further, carbon ion implantation driven enhanced PL lifetime is shown to be associated with energy transfer between V0 and the vicinal CAl. This work shows the potential of carbon doped AAO as a future candidate for developing rare earth free nontoxic phosphor. [ABSTRACT FROM AUTHOR]

The effect of oxygen partial pressure (OPP) during deposition on the structural and ferroelectric properties of epitaxial SmFeO 3 (SFO) thin films is studied in the present report. The thin films are deposited using the pulsed laser ablation method. Two (00l) oriented substrates, viz., LaAlO 3 (LAO) and niobium doped SrTiO 3 (Nb:STO), are used for the deposition of films with 35 and 170 nm thicknesses at different OPP values. The prepared films are found to be of single phase and grow in the out-of-plane configuration SFO(hh0)/LAO(00l) using x-ray 2 θ − ω and ϕ scans. The epitaxial relationship between the substrate and the film, domain twinning, is confirmed by reciprocal space map measurements. Films of higher thickness exhibit tilted twin structures, more prominently for the films prepared at lower OPP. A significant change in the leakage current is observed as a function of OPP, and the results are explained in terms of the microstructure of the films. [ABSTRACT FROM AUTHOR]

We report the modifications in the electronic properties of single phase polycrystalline BaTiO3 due to ferroelectric to paraelectric phase transition revealed by temperature dependent synchrotron based x-ray absorption and valence band spectroscopy. Valence band spectra show a strong temperature dependence of Ti-3d and O-2p hybridized states around the phase transition. It is observed that Ti-O hybridization is stronger in the paraelectric phase, which is also supported by multiplet calculations at the Ti L-edge. We also find a reduced crystal field value in the paraelectric phase than in the ferroelectric phase, which is caused by volume expansion and a reduction in tetragonal distortion. [ABSTRACT FROM AUTHOR]

Co-precipitation route synthesized undoped ZnO and Sm-substituted ZnO nanomaterials are characterized using XRD, UV–Vis-NIR spectroscopy, Raman Spectroscopy, HRTEM and XAS techniques. Rietveld-refined XRD patterns and Raman spectra correspond to wurtzite structure similar to ZnO for all samples. For Sm-substituted ZnO samples, observed fluctuating lattice parameters suggest dopant-induced agitation in host lattice. Full incorporation of Sm cation can be seen by wurtzite ZnO nanolattice but for higher doping ,Sm cation is not fully incorporated and a new cubic phase of Sm2O3 is observed with our XRD and Raman analyses. From our TEM micrographs, particle sizes of undoped ZnO and Sm-substituted ZnO samples are found between 21 and 24 nm in spherical shape for undoped ZnO and nanorods for Sm-substituted ZnO samples. Absorption spectra analyses report a decrease in bandgap energy for Sm-substituted ZnO samples from 3.20 to 3.16 eV. X-ray absorption edges of Zn L2,3 edge, O K edge and Sm M4,5 edge measurements confirm the valence state of Sm cations is + 3 and the valence state of Zn ions is + 2 along with an increase in introduction of oxygen vacancies with Sm substitution in nanolattice. These nanoparticles can be suitable alternatives for various applications like oxygen transportation, UV blockers, photocatalyst and optoelectronics. [ABSTRACT FROM AUTHOR]

We report the structural and electronic properties of single phase, polycrystalline rutile tetragonal SnO2 thin film grown on Si (100) substrate by pulsed laser deposition technique. X-ray photoelectron and resonant photoemission spectroscopic (RPES) studies divulge that Sn is present in 4+(~91%) valence state with a very small involvement of 2+(~9%) valence state at the surface. Valence band spectrum of the film shows prominent contribution due to the Sn4+ valence state. RPES measurements were performed in the Sn 4d→5p photo absorption region. This study shows that O-2p, Sn-5s, and Sn-5p partial density of states are the main contributions to the valence band of this material. The resonance behavior of these three contributions has been analyzed. Constant initial state versus photon energy plots suggest that the low binding energy feature at ~2.8 eV results from the hybridization of the O-2p and mixed valence states of Sn, while remaining features at higher binding energies are due to the hybridization between O-2p (bonding) orbitals and Sn4+ valence state. [ABSTRACT FROM AUTHOR]

In the present paper, we have investigated the structural and electronic properties of Eu2O3 thin film deposited by pulsed laser deposition technique on Si (100) substrate. The film was characterized by X-ray diffraction and photoemission measurements. X-ray photoemission studies suggest that Eu has 2+ (∼8%) and 3+ (∼92%) valence states in the film. Valence band spectrum of the film shows four features (2 eV, 4.8 eV, 7.7 eV, and 10.4 eV) with the prominent one at 7.7 eV due to the Eu3+ (4f 6) state. Resonance photoemission spectroscopy measurements have been performed in the Eu 4d → 4f photo absorption region, and thus, obtained constant initial state intensity plots suggest that the feature close to the Fermi level (∼2 eV) results from the hybridization of the O 2p and Eu2+ (4f7) states, while other features appearing at higher binding energies are due to the hybridization of the O 2p and Eu3+ (4f 6) states. [ABSTRACT FROM AUTHOR]

Interfacial atomic diffusion, reaction, and formation of microstructure in nanoscale level are investigated in W/B4C multilayer (ML) system as functions of thickness in ultrathin limit. Hard x-ray reflectivity (XRR) and x-ray diffuse scattering in conjunction with x-ray absorption near edge spectroscopy (XANES) in soft x-ray and hard x-ray regimes and depth profiling x-ray photoelectron spectroscopy (XPS) have been used to precisely evaluate detailed interfacial structure by systematically varying the individual layer thickness from continuous-to-discontinuous regime. It is observed that the interfacial morphology undergoes an unexpected significant modification as the layer thickness varies from continuous-to-discontinuous regime. The interfacial atomic diffusion increases, the physical density of W layer decreases and that of B4C layer increases, and further more interestingly the in-plane correlation length decreases substantially as the layer thickness varies from continuous-to-discontinuous regime. This is corroborated using combined XRR and x-ray diffused scattering analysis. XANES and XPS results show formation of more and more tungsten compounds at the interfaces as the layer thickness decreases below the percolation threshold due to increase in the contact area between the elements. The formation of compound enhances to minimize certain degree of disorder at the interfaces in the discontinuous region that enables to maintain the periodic structure in ML. The degree of interfacial atomic diffusion, interlayer interaction, and microstructure is correlated as a function of layer thickness during early stage of film growth. [ABSTRACT FROM AUTHOR]

The valence band offset value of 2.3 ± 0.2 eV at epitaxial NiO/Al2O3 heterojunction is determined from photoelectron spectroscopy experiments. Pulsed laser deposited thin film of NiO on Al2O3 substrate is epitaxially grown along [111] direction with two domain structures, which are in-plane rotated by 60° with respect to each other. Observation of Pendellosung oscillations around Bragg peak confirms high interfacial and crystalline quality of NiO layer deposited on Al2O3 substrate. Surface related feature in Ni 2p3/2 core level spectra along with oxygen K-edge soft X-ray absorption spectroscopy results indicates that the initial growth of NiO on Al2O3 substrate is in the form of islands, which merge to form NiO layer for the larger coverage. The value of conduction band offset is also evaluated from the measured values of band gaps of NiO and Al2O3 layers. A type-I band alignment at NiO and Al2O3 heterojunction is also obtained. The determined values of band offsets can be useful in heterojunction based light emitting devices. [ABSTRACT FROM AUTHOR]

In this paper, structural, optical and electronic properties of ZnO nanoparticles were investigated with the variation in the annealing temperature. X-ray diffraction, High-Resolution Transmission Electron Spectroscopy, Absorption spectroscopy, Raman Spectroscopy and Soft X-ray spectroscopy techniques were invoked to investigate and gauge the effect of annealing temperature on these properties. Intact Hexagonal Wurtzite phase of the nanoparticles with increasing crystallinity and spherical shape with particle size between 20 nm and 23 nm [using both X-ray Diffractometer (XRD) and High-resolution Transmission of electron microscopy (HRTEM)], blue shift of absorption peak from 372 nm to 366 nm and Optical Band Gap from 3.24 eV to 3.17 eV (UV-Vis-NIR), narrowing of E 2 H mode in Raman Spectra; all indicated enhanced crystallinity with increased annealing temperature. Effects produced by the sole variable such as annealing temperature on the indicative parameters in a definite order catapult the annealing conditions as a significant candidate for customized properties. To have a deeper insight at the electronic levels, Synchrotron-based X-ray absorption spectroscopic studies of ZnO nanoparticles were undertaken. The analysis of Soft XAS spectra showed the change in number of O 2 p and Zn 4 p unoccupied states with increasing particle size and crystallinity of ZnO nanoparticles for varying annealing temperature. Dependence of the crystallite size (D) and micro-strain (ε) on annealing temperature (Ta) calculated using XRD patterns (top left side figure), band gap energy Eg and Urbach energy Eu on annealing temperatures, measured using absorption spectra (top right side figure) and Raman spectra for the ZnO nanoparticles annealed at different temperatures (300, 400 and 500∘C) (bottom figure), showing the structural, optical properties dependence on the annealing temperature, supporting enhanced crystalline nature and increased grain sizes for the ZnO nanoparticles. [ABSTRACT FROM AUTHOR]

This paper reports the spectroscopic investigation of Ba3Zr2O7 phosphors. A series of Ba3Zr2O7: Eu3+ with the different molar concentrations (0–4 mol.%) of europium (Eu3+) ion is synthesized by the solution combustion method. The synthesized powders are characterized systematically using X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence spectroscopy, and ultraviolet–visible spectroscopy. X-ray diffraction results indicate that the synthesized powder has a tetragonal crystal structure. X-ray photoelectron spectroscopy is used to study the elemental composition of the synthesized phosphor. Field emission scanning electron microscopy result reveals that non-uniform morphology is formed. Photoluminescence spectroscopy result shows several emission peaks due to electronic transitions of Eu3+ ion, and the dominant peak is observed at 613 nm due to electric dipole transition 5D0 → 7F2. CIE coordinates of Eu3+-activated Ba3Zr2O7 phosphor is found to be (x = 0.64, y = 0.36) which gives bright red emission. The optical band gap of the phosphors is obtained from the diffuse reflectance spectrum and found in the range of 4.62–4.83 eV. [ABSTRACT FROM AUTHOR]

In this work, a well-ordered array of multiferroic magnetoelectric (ME) dot-like nanostructures of Pb(Mg1/3Nb2/3)O3]0.65–[PbTiO3]0.35 (PMN-PT)/NiFe2O4 is explored for high density and low power consuming memory devices. Ordered arrays of ferromagnetic NiFe2O4 nanodots underneath a ferroelectric PMN-PT layer were fabricated using silicon nitride based stencil masks and pulsed laser deposition techniques. The piezo-response and magnetic force microscopy (PFM) measurements reveal coexistence of magnetic and ferroelectric domains in PMN-PT/NiFe2O4 films at room temperature. The ferroelectric polarization can be switched with the electrically biased PFM tip. The ME coupling is evident in the PMN-PT/NiFe2O4 films, which is attributed to the transfer of the elastic strain from PMN-PT to NiFe2O4. The PMN-PT/NiFe2O4 nanodot films exhibit enhanced ME coupling coefficient (α) as compared to continuous bilayer PMN-PT/NiFe2O4 films, owing to the superior strain transfer efficiency in nanodot heterostructures. The nanodot films demonstrate electric-field controlled nonvolatile switching of α, which can be used to store binary information in memory devices, holding all the advantages of ferroelectric random access memory but overcoming the major disadvantage of destructive reading of polarization. The results reveal a versatile approach for fabrication of well-ordered nanodot arrays for low power consuming, high-density ME device applications. [ABSTRACT FROM AUTHOR]

Electric-field controlled magnetism is a potential way to realize strong magneto-electric (ME) coupling for nonvolatile memory applications. The electric field induced nonvolatile modulated magnetization was obtained in NiFe2O4/SrRuO3/Pb(Mg1/3Nb2/3)0.7Ti0.3O3 (PMN-PT) thin film heterostructures. The collective effect of charge and strain significantly modified the magnetization of the NiFe2O4 layer in NiFe2O4/SrRuO3/PMN-PT heterostructures. The analysis of XMCD data establishes that the cation (Fe3+/Ni2+) redistribution occurs on tetrahedral and octahedral sites in the electric field poled NiFe2O4 films, confirming the coupling between magnetism and ferroelectric properties. The films demonstrate repeatable switching of sign of ME output voltage α (α = dP/dH) in response to the applied positive and negative electric pulse, which can be used to store binary information in the nonvolatile manner. The electric-field-controlled switching of α in thin films offers an energy-efficient approach for low-power-consumption nonvolatile memory devices. [ABSTRACT FROM AUTHOR]

A prototype in situ X‐ray absorption near‐edge structure (XANES) system was developed to explore its sensitivity for ultra‐thin films of iron‐nitride (Fe‐N), cobalt‐nitride (Co‐N) and nickel‐nitride (Ni‐N). They were grown using DC‐magnetron sputtering in the presence of an N2 plasma atmosphere at the experimental station of the soft XAS beamline BL01 (Indus‐2, RRCAT, India). XANES measurements were performed at the N K‐edge in all three cases. It was found that the N K‐edge spectral shape and intensity are greatly affected by increasing thickness and appear to be highly sensitive, especially in low‐thickness regions. From a certain thickness of ∼1000 Å, however, samples exhibit a bulk‐like behavior. On the basis of the obtained results, different growth stages were identified. Furthermore, the presence of a molecular N2 component in the ultra‐thin regime (<100 Å) was also obtained in all three cases studied in this work. In essence, this prototype in situ system reveals that N K‐edge XANES is a powerful technique for studying ultra‐thin films, and the development of a dedicated in situ system can be effective in probing several phenomena that remain hitherto unexplored in such types of transition metal nitride thin films. [ABSTRACT FROM AUTHOR]

The valence and conduction band offsets of Zn1-xCd1-xO/ZnO hetero-junctions deposited by pulsed laser deposition technique were estimated by X-ray photoelectron, valence band, and UV-visible spectroscopy. Type-II band alignment (staggered gap) with ratios of conduction band to valence band offsets (ΔEC/ΔEV) was found to be 0.77 and 0.59 for Zn0.95Cd0.05O/ZnO and Zn0.90Cd0.10O/ZnO hetero-structures, respectively, which can be used in longer wavelength regime optoelectronic devices. The higher value of valence band offset as compared to conduction band offset suggests that the transport at interface is mainly due to electrons. [ABSTRACT FROM AUTHOR]

We studied localized surface plasmon resonances (LSPR) at different compositions, substrate temperatures, and mass thicknesses of Ag-Au alloy nanoparticle films grown by sequential pulsed laser deposition. The LSPRs were pronounced at all compositions of the films grown at high substrate temperature of about 300 °C as compared to those grown at room temperature. The alloy formation and composition of the films were determined using X-ray photoelectron and energy dispersive spectroscopy. Films' mass thickness and compositional uniformity along the thickness were determined using X-ray reflectometry and secondary ion mass spectroscopy. Atomic force microscopic analysis revealed the formation of densely packed nanoparticles of increasing size with the number of laser ablation pulses. The LSPR wavelength red shifted with increasing either Au percentage or film mass thickness and corresponding LSPR tuning was obtained in the range of 450 to 690 nm. The alloy dielectric functions obtained from three different models were compared and the optical responses of the nanoparticle films were calculated from modified Yamaguchi effective medium theory. The tuning of LSPR was found to be due to combined effect of change in intrinsic and extrinsic parameters mainly the composition, morphology, particle-particle, and particle-substrate interactions. [ABSTRACT FROM AUTHOR]

The spin-blockade phenomena occur in the charge-ordered systems because of the non-conservation of the spin-states of the charges across the charge hopping process. Here, we have investigated the validation of the spin-blockade phenomena in a different kind of charge-ordered system, viz. charge-disproportionated SrCoO2.5 thin film, where O-2p hole is the key parameter for such charge-ordering. It is observed with the help of the polarization-dependent O K-edge x-ray absorption spectroscopy that the spin-blockade increases with the decrease in charge-disproportionation vis-à-vis O-2p hole density in the SrCoO2.5 films. The spin-blockade has been realized in terms of the lowest energy charge fluctuation energetics in the SrCoO2.5 films. Our results provide a fundamental understanding of the spin-blockade phenomena in both the usual charge-ordered and unusual charge-disproportionated systems, which would lead to a path forward toward novel material designing. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of high mobility thin films of La-doped SrSnO 3 are reported. The mobility for the 7 % La-doped sample was found to be 228 cm 2 V - 1 s - 1 . The observed high mobility was associated with the reduced carrier effective mass and scattering centers of various scattering mechanisms. The enhancement in mobility and the increase in carrier concentration after doping reduced the resistivities of the thin films by five orders of magnitude. X-ray absorption spectroscopy and X-ray photoelectron spectroscopy revealed that La-dopant and oxygen vacancies donated the electrons in the films. Films were highly transparent (> 90 %) in the visible region. These materials have great potential to be used in optoelectronic and heterostructure devices [ABSTRACT FROM AUTHOR]

Anodized aluminum oxide (AAO) in amorphous form is shown to be a prospective phosphor for optically stimulated luminescence (OSL) by implanting 50 keV carbon ions at a fluence of 1 × 1016 ions/cm2 at room temperature. An almost 20-fold enhancement in continuous wave OSL (CW-OSL) sensitivity is obtained in carbon-doped AAO (C:AAO) by exposing to beta radiation, while an almost linear increase in CW-OSL intensity is recorded with increasing dose from 0.3 to 5 Gy. However, cathodoluminescence (CL) suggests an upsurge of oxygen vacancies, especially F+ and F22+ centers, at the cost of F center-related defects in C:AAO. Detailed X-ray photoelectron spectroscopy (XPS) analysis further reveals that the implanted carbon atoms can act as cationic impurities in AAO and stabilize the nearby F+ centers via substitution of Al3+ by C2+. The combined CL and XPS results are also shown to be capable of illustrating the CW-OSL response. This study would, therefore, be a benchmark for understanding the role of carbon in the substitutional sites of AAO for generating OSL active electron traps. [ABSTRACT FROM AUTHOR]

Here, we present the low temperature magnetic behaviour of epitaxial La0.7Ca0.3Mn0.85Al0.15O3 (LCMAO) thin film through a series of DC magnetic measurements. Overall behaviour inferred from the magnetization measurements indicate that the magnetic phases created due to Al doping induced inhomogeneous distribution of Mn3+ and Mn4+ ions and oxygen vacancies present in the system act like superspins, and the strong interaction among themselves results in the superspin glassy behaviour. Interactions among the superspins are marked by the aging and zero filed memory effects. The glassy magnetic phase in LCMAO is found to follow the hierarchical model of spin glasses. [ABSTRACT FROM AUTHOR]

We report on the magnetic, electrical, and magnetotransport properties of La0.7Ca0.3Mn1-XAlXO3 (X=0, 0.05, 0.15) thin films grown on LaAlO3 (001) substrate. It is observed that the low temperature ferromagnetic phase of La0.7Ca0.3MnO3 transforms into metastable magnetic state in 15 at. % Al doped sample, which has been characterized using long-time relaxation measurement as well as different temperature sweep rates (during cooling and heating) of magnetization measurements. Our results clearly show that the magnetic transition in this film is connected with the kinetics of first order phase transition. The metastable magnetic phase also shows increased magnetoresistance. [ABSTRACT FROM AUTHOR]

Ferromagnetic Co-doped TiO2 thin films at room temperature have been synthesized by RF sputtering and ion-irradiated with 100 MeV Au ions. The surface roughness of the film increases with increasing Au-ion fluence. Kerr microscopy measurements at room temperature give isotropic hysteresis loop with negligible coercivity, which gets modified into in-plane uniaxial magnetic anisotropy after anion fluence of 5×1011 ions/cm2. Further ion-irradiation reduced the coercivity of the film. X-ray magnetic circular dichroism (XMCD) measurements have been performed in total electron yield mode, to investigate the effects of ion-irradiation on magnetic properties of the Co-doped TiO2 thin films. From the XMCD analysis, we observed that the total magnetic moment of Co atoms in case of as-deposited film is 1.771 ± 0.016 μ B . After the ion-irradiation it became 0.3818 ± 0.014 μ B a t r o o m t e m p e r a t u r e. [ABSTRACT FROM AUTHOR]

Two thin films of SrMnO3 (SMO) were grown on LAO (LaAlO3) (110) substrate by pulsed laser deposition (PLD) technique with different oxygen stoichiometry. From low-temperature magnetization measurements, it is observed that both films show a clear ferromagnetic kind of behavior. Electronic structure of both films has been investigated by using soft x-ray absorption spectroscopy (XAS) and photoemission spectroscopy (PES). It is revealed that the Mn-O hybridization is hugely modified due to oxygen stoichiometry, with its consequences on their magnetic properties. [ABSTRACT FROM AUTHOR]

Composites of Li1.3Al0.3Ti1.7(PO4)3 (LATP) with Li+ ion containing polymer polyethylene oxide (PEO), viz. 5LiCF3SO3-95[PEO1−xLATPx], are prepared in a wide composition range (0 ≤ x ≤ 0.7). A maximum conductivity of ~ 10−4 Ω−1 cm−1 at 45 °C has been achieved for a composition x = 0.7 (70 LATP). With increase in LATP content, Li+ ion transport number systematically increases, i.e., from ~ 0.12 for 0 LATP to 0.46 for 70 LATP. Ionic mobility also exhibits a gradual rise with LATP content and attains a value ~ 2 orders of magnitude higher for 70 LATP than 0 LATP. Further, the K-edge energy of ether oxygen, obtained from X-ray absorption near-edge structure spectra, does emphasize decoupling of Li+ ions from PEO matrix, particularly for large LATP content. Our investigations suggest that such hybrid films are competitive candidates for solid ionic devices. All-solid-state supercapacitors fabricated using these films demonstrate a capacity of ~ 2–4 F-g−1. [ABSTRACT FROM AUTHOR]

Depth profiling type of measurement has been performed on the Co(100 Å)/Cu(50 Å) bilayer thin film. Valence band photoemission spectra were recorded at 50 eV photon energy as a function of sputtering time. The motivation of the present work is to understand the electronic structure of the buried Co/Cu interface and the nature of intermixing in the Co and Cu layers. X-ray reflectivity and transmission electron microscopy corroborate with the photoemission results and shows a very broad intermixed Co-Cu interface. The valence band of intermixed Co/Cu interface shows the Co and Cu 3d states which are considerably shifted towards higher and lower binding energy, respectively, as compared to the bulk elemental Co and Cu 3d states. The experimental observations are explained with the help of calculations based on projected augmented wave pseudopotential method using density functional theory. The origin and the shift of feature in the valence band of the Co-Cu interface are mainly due to the formation of two different Co and Co-Cu mixed nanoclusters. [ABSTRACT FROM AUTHOR]

For a detailed study on the semiconductor to metal transition (SMT) in ZnO thin films doped with Al in the concentration range from 0.02% to 2%, we grew these films on (0001) sapphire substrates using sequential pulsed laser deposition. It was found that the Al concentration in the films increased monotonically with the ratio of ablation durations of the alumina and ZnO targets used during the deposition. Using x-ray photo electron spectroscopy, it was found that while most of the Al atoms occupy the Zn sites in the ZnO lattice, a small fraction of the Al also gets into the grain boundaries present in the films. The observed SMT temperature decreased from ∼270 to ∼50 K with increase in the Al concentration from 0.02% to 0.25%. In the Al concentration range of ∼0.5% to 2%, these doped ZnO films showed metallic behavior at all the temperatures without undergoing any SMT. A theoretical model based on thermal activation of electrons and electron scatterings due to the grain boundaries, ionic impurities, and phonons has been developed to explain the observed concentration and temperature dependent SMT. [ABSTRACT FROM AUTHOR]

We report the effect of oxygen partial pressure (OPP) and 5% Fe doping on the structural, electrical, and magnetic properties of MoOx thin films on c-Al2O3 substrate prepared by pulsed laser deposition technique. Detailed analyses of the structural properties suggest that the grown phase of molybdenum oxides and its orientation strongly depend on the OPP as well as Fe doping. Undoped and Fe doped α-MoO3 films formed at 350 mTorr OPP value show insulating character, where as MoO2 films formed at lower OPP values reveal metallic behavior. Resistivity minima are observed in Fe doped MoO2 films, which could be due to weak localization effect or Kondo scattering of the conduction electrons from the Fe impurities. Interestingly, all the Fe doped molybdenum oxide films show magnetic hysteresis at room temperature irrespective of their insulating (MoO3 phase) or metallic (MoO2 phase) behavior. [ABSTRACT FROM AUTHOR]

We study the structural and electronic properties of Fe doped (4-8 at. %) and undoped TiO2 thin films deposited by pulsed laser deposition on Si(111) substrate. The films grow in single phase anatase structure of TiO2 as revealed by x-ray diffraction and Raman spectroscopy measurements. The Fe doped films reveal room temperature magnetic hysteresis behavior. We have probed the electronic environment of Fe in TiO2 matrix and its coupling to the cations, using photoelectron spectroscopy measurements. Photoelectron spectroscopic studies reveal the ionic state of Fe in TiO2, precluding the formation of Fe metal clusters. Valence band spectra of these films suggest that it primarily consists of O-2p derived state, however, Fe derived state is also observed in Fe doped films. Resonance photoelectron spectroscopy studies indicate that Fe ions are hybridized with Ti3+ defect states. [ABSTRACT FROM AUTHOR]

We have studied the modification in the electronic properties of pulsed laser deposited CeO2 thin films due to Fe doping (2 and 6 at %), with the help of x-ray photoemission spectroscopy (XPS) and resonance photoemission spectroscopy (RPES) measurements. XPS results indicate the ionic state of Fe in the Fe doped films, ruling out the possibility of Fe metallic clusters. Valence band spectra of CeO2 show an additional feature after Fe doping, suggesting its incorporation in the CeO2 matrix. RPES studies on these films reveal the hybridization between oxygen vacancy induced Ce localized states and Fe derived states. [ABSTRACT FROM AUTHOR]

The effects of doping on magnetic and electrical transport mechanism of polycrystalline samples La0.7Ca0.3Mn1-xAlxO3 (x=0,0.02,0.04,0.06,0.08,0.1) have been investigated. Magnetization data reveal that long-range ferromagnetic ordering persists in all samples and the saturation moment decreases linearly as x increases. Resistivity data have been fitted with the variable range hopping model to estimate the density of state at Fermi level. It was observed that the substitution of Al in the series leads to a decrease in conductivity of the doped manganites samples, with conduction being controlled by the disorder induced localization of charge carriers. [ABSTRACT FROM AUTHOR]