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It has been established that laser-patterned artificial interfaces prompt a large rise in the resistivity and magnetoresistance of La2/3Sr1/3MnO3 thin films. The magnetization of the patterned region was found to be lower than that of the rest of the film.

Research into the effect of distinct growth parameters that influence the roughness and surface morphology of La2/3Ca1/3MnO3 expitaxial thin films grown by rf sputtering is presented. It is concluded that the film roughness is very dependent on its thickness.

A study was conducted to analyze the growth of epitaxial La(sub 2/2)Sr(sub 1/3)MnO3 thin films on buffered Si(001) substrates. The films were prepared by pulsed laser deposition using a KrF excimer laser. The magnetic anisotropy of the fimls were then obtained. Experimental results indicated that the suitable choice of the buffer heterostructure promotes the determination of epitaxial (00h).

Using a combination of advanced characterization tools (positron annihilation spectroscopy, conductive-tip atomic force microscopy, and high-field magnetotransport), we have studied the extension, origin and properties of the high mobility electron gas (HMEG) generated by etching the SrTiO3 surfaces with Ar+ ions. Contrary to previous assumptions, we show that this HMEG is not confined to nanometric thickness but extends to a few micrometer from the surface. We discuss this unanticipated large spatial extension in terms of the striking large diffusion of oxygen vacancy-related defects. [ABSTRACT FROM AUTHOR]

An understanding of the thin film structure and properties of ilmenite is crucial for the future study of ilmenite-hematite solid solutions for spintronics applications. Here, we report a systematic study of the FeTiO3±δ thin film structure as a function of the deposition parameters during pulsed laser ablation. The films are found to be crystalline and epitaxial on α-Al2O3(0001) substrates for a wide range of substrate temperatures and oxygen pressures. Initial stages of the film growth and in-plane lattice relaxation were investigated. The increase in the a lattice parameter of up to 6% above its bulk value was observed and is most probably due to the buckling of a few ilmenite monolayers at the film/substrate interface because of a significant compressive stress induced on the film by sapphire substrate. In spite of the absence of a diffraction peak corresponding to the ordered R3 phase, these films consist of pure ilmenite phase with negligible net magnetization. Film conductivity is tuned over three orders of magnitude in the studied oxygen pressure range and is comparable to that of bulk ilmenite at pressures above 10 mTorr. [ABSTRACT FROM AUTHOR]

We report on the growth of thin films of the diluted magnetic oxide Co-doped La0.5Sr0.5TiO3-δ on SrTiO3 and LaAlO3 substrates. The films are ferromagnetic at room temperature, with no indications of parasite phases from high-resolution x-ray diffraction experiments. The structural mismatch with the substrate is shown to have a strong impact on the growth mechanisms and, consequently, on the surface morphology. In this sense, to grow the films on SrTiO3, for which the mismatch is minimized, appears to be more appropriate for the future integration of Co-doped La0.5Sr0.5TiO3-δ layers into heterostructures for perpendicular transport. [ABSTRACT FROM AUTHOR]

We report on the growth of thin films and heterostructures of the ferromagnetic-insulating perovskite La0.1Bi0.9MnO3. We show that the La0.1Bi0.9MnO3 perovskite grows single phased, epitaxially, and with a single out-of-plane orientation either on SrTiO3 substrates or onto strained La2/3Sr1/3MnO3 and SrRuO3 ferromagnetic-metallic buffer layers. We discuss the magnetic properties of the La0.1Bi0.9MnO3 films and heterostructures in view of their possible potential as magnetoelectric or spin-dependent tunneling devices. [ABSTRACT FROM AUTHOR]

We report on the growth of thin films and heterostructures of the ferromagnetic-insulating perovskite La0.1Bi0.9MnO3. We show that the La0.1Bi0.9MnO3 perovskite grows single phased, epitaxially, and with a single out-of-plane orientation either on SrTiO3 substrates or onto strained La2/3Sr1/3MnO3 and SrRuO3 ferromagnetic-metallic buffer layers. We discuss the magnetic properties of the La0.1Bi0.9MnO3 films and heterostructures in view of their possible potential as magnetoelectric or spin-dependent tunneling devices. [ABSTRACT FROM AUTHOR]

A combination of advanced characterization tools are used for studying the extension, origin and properties of the high mobility electron gas (HMEG) generated by etching the SrTi[O.sub.3] surfaces with [Ar.sup.+] ions. The studies have shown that the HMEG is not confined to nanometric thickness but has extended to a few micrometers from the surface and this large spatial extension is discussed terms of the striking large diffusion of oxygen vacancy-related defects.

A systematic study is conducted to explain the growth, as well as the structural properties of the FeTi[O.sub.3[plusmn][delta]] epitaxial thin films. The films are shown to exhibit a crystalline and epitaxial structure on the [alpha]-[Al.sub.2][O.sub.3](0001) substrates over a wide range of temperatures and pressures.

Heterostructures associating half-metallic [La.sub.(2/3)]Sr.sub.(1/3)Mn[O.sub.3] (LSMO) bottom electrodes and ferromagnetic [La.sub.(0.1)]Bi.sub.(0.9)]Mn[O.sub.3] (LBMO) tunnel barriers are grown. The LBMO films show an insulating behavior and a ferromagnetic character that are both preserved down in very low thicknesses.

The observation of a large tunnel magnetoresistance at low temperature in [La.sub.(2/3)][Sr.sub.(1/3)]Mn[O.sub.3]/SrTi[O.sub.3]/Ni[Fe.sub.2][O.sub.4] junctions are reported. The results of the observation reveal the occurrence of a spin polarization of up to 45% for Ni[Fe.sub.2][O.sub.4], which stays constant upto ~300 Kelvin.

The influence of the substrates LaAlO3 (LAO) or SrTiO3 (STO) on the growth and properties of thin films of the diluted magnetic oxide Co-doped La(sub 0.5)Sr(sub 0.5)TiO(sub 3-delta) is analyzed. It is shown that the growth on STO results in films with better structural properties and a much smoother surface morphology, compatible with the integration of Co-LSTO layers into heterostructures.

The growth of the thin films and heterostructures of the ferromagnetic-insulating perovskite La(sub 0.1)Bi(sub 0.9)MnO(sub 3) is reported. The reports show that the La(sub 0.1)Bi(sub 0.9)MnO(sub 3) perovskite grows single phased, epitaxially, and with a single out-of-plane orientation either on SrTiO3 substrates or onto strained La(sub 2/3)Sr(sub 1/3)MnO(sub 3) and SrRuO(sub 3) ferromagnetic-metallic buffer layers.

The magnetotransport properties of nanometric La(sub 2/3)Ca(sub 1/3)MnO3 (LCMO) thin films grown on different substrates, including the perfectly matched lattices, are evaluated to examine the effect of strain. It was seen that the charge localization led to a weakening of the magnetic interactions and a decrease of the Curie temperature and the magnetic and transport properties of nanometric films were critically dependent on the microstructure.

We have grown heterostructures associating half-metallic La2/3Sr1/3MnO3 (LSMO) bottom electrodes and ferromagnetic La0.1Bi0.9MnO3 (LBMO) tunnel barriers. The layers in the heterostructures have good structural properties and top LBMO films (4 nm thick) have a very low roughness when deposited onto LSMO/SrTiO3(1.6 nm) templates. The LBMO films show an insulating behavior and a ferromagnetic character that are both preserved down to very low thicknesses. They are thus suitable for being used as tunnel barriers. Spin-dependent transport measurements performed on tunnel junctions defined from LSMO/SrTiO3/LBMO/Au samples show a magnetoresistance of up to ∼90% at low temperature and bias. This evidences a spin-filtering effect by the LBMO layer, with a spin-filtering efficiency of ∼35%. [ABSTRACT FROM AUTHOR]

Ultrathin epitaxial films of NiFe2O4, when grown under specific conditions, show a large enhancement of their magnetic moment and electrical conductivity. This allowed us to use such layers as electrodes in magnetic tunnel junctions. In this paper, we report on the observation of a large tunnel magnetoresistance at low temperature in La2/3Sr1/3MnO3/SrTiO3/NiFe2O4 junctions. From these results we infer a spin polarization of up to 45% for NiFe2O4, which stays constant up to ∼300 K. NiFe2O4 can therefore be considered as an alternative to Fe3O4 as a high-temperature spin-polarized Fe oxide. Furthermore, our findings provide a way to design materials for spintronics based on the stabilization of nonthermodynamically stable magnetic phases of spinel oxides. [ABSTRACT FROM AUTHOR]

By using magnetotransport measurements as well as nuclear magnetic resonance as local magnetic probe, we conclusively show that, irrespective of the film/substrate structural mismatch and film thickness, there are nonconductive regions at the film/substrate interface. We thus discard dimensional effects and structural mismatch as the main reasons for the suppression of conductivity and the weakening of the ferromagnetic coupling in nanometric thin films of manganites. We shall argue that this behavior is related to a charge localization which also leads to a weakening of the magnetic interactions and a decrease of the Curie temperature. [ABSTRACT FROM AUTHOR]

In this work, we report on the impact of distinct growth parameters that affect the roughness and surface morphology of La[sub 2/3]Ca[sub 1/3]MnO[sub 3] epitaxial thin films grown by rf sputtering, namely, the film thickness and the deposition temperature. Data for films with thicknesses ranging from 2.4 to 108 nm will be presented. A correlation with transport measurements is also reported: whereas films thicker than 6 nm show the typical metal-to-insulator transition, the thinner film is insulating. The resistivity is strongly enhanced when decreasing film thickness. Nuclear magnetic resonance measurements have been used to monitor the relative concentration of the localized Mn[sup 4+] and delocalized Mn[sup 3+/4+] states. It is found that the relative intensity of the delocalized Mn[sup 3+/4+] configuration (I[sup 3+/4+]) progressively lowers when reducing film thickness. Of significance could be the observation that I[sup 3+/4+] remains finite for the thicknesses co! rresponding to insulating films, thus suggesting that an electrically inhomogeneous state is formed in a region close to the interface with the substrate. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In this study, we have performed magneto-optical Kerr effect (MOKE) measurement on epitaxial La[sub 2/3]Sr[sub 1/3]MnO[sub 3] thin films containing artificial interfaces created by laser-patterning the SrTiO[sub 3] substrate. The observed increase of the resistivity and of the high-field magnetoresistance when measuring the films across the interface arrays are related to the reduction of the magnetization of the interfaces with respect to the rest of the film. As observed by the local MOKE probe, the structural disorder in the manganite film induced by the underlying patterned substrate leads to a large spin disorder responsible for a strong high-field susceptibility of the resistance. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Studies the growth of epitaxial lanthanum-strontium-manganite thin films on buffered silicon (001) substrates. Experimental details; Results and discussion.

We describe the growth, structural, and functional characterization of BiFeO3/YBa2Cu3O7-δ ferroelectric/superconductor heterostructures. High-structural-quality bilayers are obtained, which display good ferroelectric and superconducting properties. We demonstrate that an unusually strong field-effect modulation of the YBa2Cu3O7-δ superconducting critical temperature can be produced upon ferroelectric switching of the BiFeO3 overlayer, and we show that this effect is non-volatile and reversible. [ABSTRACT FROM AUTHOR]

Ultrathin epitaxial films of NiFe2O4, when grown under specific conditions, show a large enhancement of their magnetic moment and electrical conductivity. This allowed us to use such layers as electrodes in magnetic tunnel junctions. In this paper, we report on the observation of a large tunnel magnetoresistance at low temperature in La2/3Sr1/3MnO3/SrTiO3/NiFe2O4 junctions. From these results we infer a spin polarization of up to 45% for NiFe2O4, which stays constant up to ∼300 K. NiFe2O4 can therefore be considered as an alternative to Fe3O4 as a high-temperature spin-polarized Fe oxide. Furthermore, our findings provide a way to design materials for spintronics based on the stabilization of nonthermodynamically stable magnetic phases of spinel oxides. [ABSTRACT FROM AUTHOR]