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We have grown IrO2 thin films on TiO2(110) substrates to determine the pulsed laser deposition growth window for iridates. Relaxed IrO2 films were obtained at a growth temperature of 500 °C and background oxygen pressure of 100 m Torr; otherwise, either pure Ir metal films or evaporative Ir loss were observed. Although x-ray Φ-scan measurement indicated that the films were epitaxial, a distinct grain structure was seen by atomic force microscopy and transmission electron microscopy. The grain boundaries were found to limit the conductivity of films at low temperature. It appeared that strain relaxation leads to stacking faults at grain boundaries.

Closed-loop optimization of epitaxial titanium nitride (TiN) thin-film growth was accomplished using metal-organic molecular beam epitaxy (MO-MBE) combined with a Bayesian machine-learning technique and reduced the required number of thin-film growth experiments. Epitaxial TiN thin films grown under the process conditions optimized by the Bayesian approach exhibited abrupt metal–superconductor transitions above 5 K, demonstrating a new approach to the efficient development of less-studied materials, such as transition metal nitrides. The combination of the thin-film growth technique and Bayesian approach is expected to pave the way toward accelerating the development of the automated operation of thin-film growth apparatuses.

We have fabricated epitaxial Pr 0.8 Ca 0.2 MnO 3 (PCMO) insulator layers sandwiched between Al top electrodes and epitaxial La 0.6 Sr 0.4 MnO 3 bottom electrode layers on (LaAlO 3 ) 0.3 –(Sr 2 AlTaO 6 ) 0.7 (1 0 0) substrates. Various sizes of metal/insulator/metal device structures were formed by photolithography and Ar ion milling. Device size dependence of Al/PCMO interface resistances was well fitted by series-parallel equivalent circuit, indicating several types of different resistance components exist at the Al/PCMO interfaces. These different resistance components suggest that defects might distribute inhomogeneously at the Al/PCMO interfaces which exhibit the resistance switching.

We have studied the effect of deposition conditions and strain on the phase stability, grain structure, grain orientation, crystallinity, and magnetism of InFeCoO 4 spinel thin films grown on single-crystal (0 0 1) SrTiO 3 (STO) and (0 0 1) MgO substrates. The growth window for good-quality films exhibiting uniform orientation was observed to be very narrow with deviations from optimal conditions resulting in highly disordered growth characterized by mixed (0 0 1) and (1 1 1) type orientations, expanded out-of-plane lattice constants, and reduced symmetry for the (0 0 1) oriented grains. Bulk-like magnetic properties could be obtained in films grown on STO under optimal conditions, whereas significantly lower values for saturation magnetization and T C were observed for the disordered samples. The absence of frequency-dependent components in AC-magnetization measurements indicates the absence of a glassy state previously observed in bulk InFeCoO 4 . The significantly smaller grain size of the samples grown on MgO at optimal conditions resulted in depressed T C in addition to a strong superparamagnetic effect below 20 K.

We have fabricated epitaxial La 1.2 Sr 1.8 Mn 1.7 Ru 0.3 O 7 thin films with n =2 Ruddlesden–Popper (RP) structure on TiO 2 -terminated and SrO-buffered SrTiO 3 (0 0 1) single-crystal substrates. It is shown that even small deviation from the narrow growth window results in the nucleation of (AO) 2 double layers in random directions and the loss of the desired structure. The atomic layer ordering at the interface between the thin films and SrTiO 3 substrates was studied by high-pressure, in situ reflection high-energy electron diffraction and transmission electron microscopy. It is demonstrated that growth on TiO 2 -terminated SrTiO 3 commences with the nucleation of two perovskite sub-units before the first (AO) 2 double-layer forms. To obtain a sharp RP/SrTiO 3 interface structure, it is necessary to buffer the TiO 2 -terminated SrTiO 3 substrate with a sub-unit cell SrO layer before the deposition of the RP film.

Synthesis of continuous composition-spread (CCS) thin films is widely recognized in combinatorial material science as a powerful technique for rapidly investigating the properties of new functional materials. However, there are very few reports of CCS organic thin films due to the fact that the thermal evaporation method with Knudsen cells, which is commonly used to fabricate organic thin films in vacuum, does not offer the necessary level of deposition rate control as, for example, does pulsed laser deposition (PLD). We have successfully fabricated organic CCS thin films of pentacene and 6,13-pentacenequinone by continuous-wave laser molecular beam epitaxy (CWL-MBE), which we developed as a new fabrication method for organic thin films. The composition-spread films were characterized systematically by ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, atomic force microscopy, and two-probe conductivity measurements. The present work brings the advantages of high-throughput parallel synthesis and systematic characterization to the field of organic electronics, allowing for quick exploration and rapid optimization of organic functional materials and devices.

We have used photoelectron emission microscopy (PEEM) and X-ray magnetic circular dichroism (XMCD) to study the effect of thin film thickness on the magnetic domain formation in La 0.6 Sr 0.4 MnO 3 samples that were epitaxially grown on stepped SrTiO 3 (0 0 1) substrates. The magnetic image exhibited a stripe structure elongated along the step direction, irrespective of film thickness, suggesting that uniaxial magnetic anisotropy induced by step-and-terrace structures plays an important role in the magnetic domain formation. Additional domains evolved gradually with increasing film thickness. In these domains, the direction of magnetization differed from the step direction due to biaxial magneto-crystalline anisotropy. The evolution of additional magnetic domains with increasing film thickness implies that a competition exists between the two anisotropies in LSMO films.

We have performed an in situ photoemission spectroscopy (PES) of well-ordered surfaces of high-quality epitaxial La1−x Srx MnO3(LSMO) thin films to investigate the temperature-dependent changes in the electronic structure of LSMO in detail. For ferromagnetic metal LSMO with x = 0.4 , the spectral intensity of the e g states near the Fermi level ( E F ) significantly increases with decreasing temperature. This result suggests that the stabilization of ferromagnetic ordering causes the enhancement of spectral weight near E F .

The structure of a passivating sulfide layer on Ge (0 0 1) substrates treated in an aqueous sulfide solution is investigated using Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), and coaxial impact-collision ion scattering spectroscopy (CAICISS). It is found from XPS analysis that the contribution from twofold co-ordinated Ge atoms is dominant in the S-treated Ge surface. The incident and azimuth angle dependencies of the Ge signal intensity are compared between the S-passivated and clean Ge surfaces in CAICISS measurements. The azimuth angle dependence exhibits clear 4-fold symmetry in both the S-passivated and the clean surfaces. From the incident angle dependence along [1 0 0] direction, almost the same shadowing and focusing effects are observed in both the surfaces. These results suggest that Ge surface is passivated by S atoms occupying bridge positions between adjacent surface Ge atoms. In order to examine the effect of S-passivation of Ge surfaces on the interface electrical properties, we perform I–V measurements of Au/S-passivated Ge Schottky diodes. It is found that the S-passivation is effective for obtaining uniform diode characteristics.

Informatics tools are an important part of the high-throughput or combinatorial materials development process. Particularly for thin film studies, the rate of sample synthesis and characterization has increased to a point where the throughput of the whole materials development process is limited by the ability to process the characterization data and design new experiments. We describe in this work software tools that we have developed to solve the data management problems. In particular, we discuss the use of extensible markup language (XML) to address the problem of representing structurally varied experimental data in a data management system without having to make modifications to the core software parts whenever the materials processing or characterization tools or sample and data handling procedures change.

The pulsed laser deposition (PLD) process was studied in detail during oxide thin film growth by constructing a sophisticated PLD chamber combined with an energy-stable excimer laser. It was revealed that the transmitting laser energy at the entrance view port decreased exponentially with deposition runs, roughly by A e−0.02x%, where A is the original transmission and x is the run number, and transmission loss could become considerable (up to 90%) in 100 deposition runs. In addition, area of the focused spot on the target was found a function of charging high voltage, which is a parameter of excimer laser operation, even through a slit forming rectangular sharp-edge beam profile. Laser energy density is one of the most important parameter governing grown film properties, and therefore accurate laser energy and spot area calibration is vital for reproducible film growth. In course of this study, the importance of spot area as well as the energy density is discussed in the view of deposition rate.

We have studied the transport properties of thin LaTiO3 films, grown on NdGaO3 and SrTiO3 substrates. In case of films grown on NdGaO3 we see a sharp increase of film resistivity when the film thickness drops below 18 nm. This appears to correspond to a surface depletion layer in the films. We could avoid the detrimental effects of surface states by growing LaTiO3 films on SrTiO3 substrates and covering the LaTiO3 layers with a SrTiO3 cap layer. In this case we succeeded in fabricating isolated LaTiO3 layers, sandwiched between SrTiO3, that remained metallic down to 4 K. This work shows that it is feasible to use the LaTiO3/SrTiO3 system for growing metallic nanostructure arrays.

We have investigated the effect of interface states on the performance of a field-effect transistor composed of a SrTiO 3 (100) single crystal as a channel and an amorphous CaHfO 3 layer as a gate insulator. The amorphous CaHfO 3 gate insulator layer, which was grown at a pressure above 1 mTorr by pulsed laser deposition (PLD), had a breakdown field of over 5 MV/cm. The transistors deposited under “hard” ablation conditions, at a laser fluence of ∼1.2 J/cm 2 , showed a normally on conducting behavior even at zero gate bias. An annealing treatment was found to decrease the interface conductivity by filling oxygen vacancies and the annealed devices exhibited clear enhancement-type transistor action.

We have studied the domain structure formation in annealed BaTiO 3 films grown on SrTiO 3 . We show that it is possible to utilize the 2.28% lattice mismatch strain at the SrTiO 3 /BaTiO 3 interface to obtain uniaxially c -axis-oriented BaTiO 3 films with a thickness of up to about 200 nm. This thickness is much larger than the typical critical thickness for BaTiO 3 films on SrTiO 3 and such films therefore can potentially be useful for optical waveguide applications. We also looked at the polarization properties of the uniaxial BaTiO 3 films. Our measurements and analysis indicate that the heavily distorted interface region, with a thickness of approximately 2 nm is non-ferroelectric.

We have performed in situ photoemission and O 1s X-ray absorption studies of La 1−x Sr x FeO 3 ( 0 ≤ x ≤ 0.67 ) epitaxial thin films grown by laser molecular beam epitaxy. We found that hole doping induces spectral weight transfer from below the Fermi level to above it across the gap in a highly non-rigid-band-like manner. We also observed the temperature dependence on the spectra of the x = 0.67 sample, which shows a charge disproportionation at 190 K. With decreasing temperature, we observed gradual changes of the spectra with spectral weight transfer primarily within the e g band.

The chemical properties and electronic structures of atomically flat SrTiO 3 (0 0 1) substrates with various surface treatments have been investigated by high-resolution synchrotron-radiation photoemission spectroscopy. We have found that an annealing process causes the segregation of Sr oxides at the TiO 2 -terminated surface. We demonstrate that the use of water-cleaning process is effective as a removal technique for Sr oxides segregated on TiO 2 -terminated surfaces with preserving the surface morphology and chemical bonding states of the topmost TiO 2 -terminated surfaces.

Highly c-axis oriented epitaxial Ru(Eu1.5Ce0.5)Sr2Cu2O10−δ (Ru-1222) thin films were grown on SrTiO3 (0 0 1) substrates by a novel growth technique, flux-assisted reactive solid phase epitaxy. The films grew epitaxially as (1 0 0)Ru-1222//(1 0 0)SrTiO3 with excellent crystallinity and atomically flat terraces and steps. The magnetization data are consistent with that reported for bulk Ru-1222 samples. The films are suggested to be granular superconducting. Although zero resistance was not obtained at temperatures down to 5 K, the onset of superconducting transition was observed at about 25 K within the ferromagnetic order.

Solid state combinatorial synthesis of oxide thin films is an attractive proposition due to the large number of compositions that could have potentially useful properties. Thin film growth, however, presents a unique set of problems related to the formation of heterointerfaces. Although this problem affects mostly the study of heterostructures, even simple film growth has to handle the substrate-film interface. We have developed a technique for growing lattice constant tunable Ba 1-x Sr x TiO 3 (BSTO)/BaTiO 3 (BTO) buffer layers on SrTiO 3 (STO) substrates in order to study the effects of lattice strain in a systematic way in combinatorial thin film libraries. We show that by combining low temperature deposition and high temperature annealing, it is possible to grow buffers with an in-plane lattice constant gradient in the range of 3.9-4.02 A using a composition spread Ba 1-x Sr x TiO 3 layer.

Wide-gap insulator films, CaZrO3, CaHfO3, LaGaO3, and NdGaO3, were grown on SrTiO3(1 0 0) substrates with the aim of obtaining a gate insulator for epitaxial oxide devices. We show that CaZrO3 and CaHfO3 films were epitaxial and had a multi-domain in-plane structure due to their highly distorted perovskite structure. Most of the LaGaO3 and NdGaO3 films were polycrystalline, and therefore showed relatively high leak currents. CaHfO3 had the best crystallinity among these four materials.

We have grown nitrogen-doped ZnO (ZnO:N) films by laser molecular-beam epitaxy. The use of lattice-matched ScAlMgO 4 substrates prevented the degradation of crystallinity induced by the nitrogen incorporation to the films. Despite this improvement, we have not obtained ZnO:N films which showed p-type conductivity. We studied the optical properties of these ZnO:N films. Donor–acceptor pair (DAP) luminescence was observed. The results indicate the formation of an acceptor state. The energy position of the DAP luminescence is lower than that reported by Look et al. [Appl. Phys. Lett. 81 (2002) 1830]. The DAP luminescence band shifts to lower energy with increasing nitrogen concentration. A photoluminescence recombination possibly due to the free-electron-to-acceptor (FA) transition was observed at temperatures higher than 40 K. The acceptor ionization energy was estimated from the energy position of the FA luminescence to be 266 meV.

We have successfully fabricated high-quality thin film of Ca3Co4O9, an oxide with superior thermoelectric properties, on a lattice matched TiO2 (1 0 0) substrate using PLD. In order to investigate the effect of elemental substitution on thermoelectric properties, we fabricated a composition-spread library of (Ca1−xBax)3Co4O9 (0≤x≤0.2), having linear compositional variation x along one direction of the substrate surface. A pin-probe type multi-channel measurement system was developed to quickly measure the thermoelectric properties (Seebeck coefficient and electric conductivity) of the library for the rapid characterization. The good correspondence of the data for Ca3Co4O9 film with those for bulk sample verifies that we can accelerate the exploration of thermoelectric oxides at least 10 times faster than the conventional one-by-one approach.

A new combinatorial pulsed laser deposition system has been developed for rapid optimization of epitaxial growth process by using a carrousel type masking plate. Under in-situ monitoring of growing surface with reflection high energy electron diffraction, eight films with different compositions or preparation parameters can be fabricated on a single substrate. By using this system, we have succeeded in the one lot optimization of YBa2Cu3O7-d(YBCO), PrGaO3, SrO and BaO film growths on the B-site (TiO2) terminated SrTiO3(001) substrates. Key results from these experiments include the high sensitivity of YBCO film crystallinity to the laser focusing as well as of growth behavior of epitaxial SrO and BaO films to the crystal habit with the underlying atomic layers.

In order to elucidate the dynamics of coalescence of La 0.6 Sr 0.4 MnO 3 nanostructures on SrTiO 3 (1 0 0), we have investigated the relationship between the electronic states of La 0.6 Sr 0.4 MnO 3 and the surface morphology of nanostructures, by using photoelectron spectroscopy and local probe microscopy. When the La 0.6 Sr 0.4 MnO 3 nanodots are heated from 700 to 800 °C, the average nanodot size increases, and the core level peaks of Mn 2p and La 3d do not change. In addition, the observed nanodot height is always 0.4 nm. Therefore, when the nanodots coalesce, they are laterally grown, maintaining the perovskite manganese structure. On the other hand, when nanowire structures are formed along the steps by heating the sample above 1000 °C, the Mn 2p peaks vanish, although the La 3d spectrum does not change. Therefore, upon this process, Mn atoms of the island dissolve into the bulk of SrTiO 3 (1 0 0), and consequently, the remaining species migrate to steps on the surface, resulting in the formation of step-decorated nanowire perovskite structures.

We have designed a series of combinatorial pulsed laser deposition (PLD) systems. The deposition chambers are similar to traditional PLD chambers except for the addition of movable masks close to the sample surface. We describe three different masking geometries, involving a carousel design and linear masks. The masking accuracy has been determined by measuring the film thickness variation at the edge of a cell in a combinatorial thin film library. Compositional variation has been observed at the cell edge using a scanning microwave microscope. It was found that a transition region, up to 200 μm in width, is unavoidable at cell edges using the present masking system. This puts a limit of 256 cells in a library chip fabricated on a typical 15 mm ×15 mm single crystal substrate. The problem can be avoided when composition spread samples are used instead of isolated cells. In that case the effective library density is determined by the spatial resolution of the analysis equipment.

In-plane lattice spacing oscillation was observed as functions of surface coverage and growing film thickness by reflection high-energy electron diffraction during the growth of strained BaTiO3 and unstrained SrTiO3 epitaxial layers on SrTiO3(1 0 0). For BaTiO3/SrTiO3, the oscillation continued until the critical thickness is reached, whereas for SrTiO3/SrTiO3, oscillation was observed only at the initial few monolayer growth. The origin of oscillations is discussed in relation to the non-tetragonal elastic distortion occurring at the free edges of 2D single monolayer islands. The amplitude of the oscillation strongly depended on the island size and density.

We have studied the role of nucleation and surface migration on the growth mode and crystal quality of SrTiO 3 and La 0.6 Sr 0.4 MnO 3 (LSMO) films. Reflection high-energy electron diffraction (RHEED) was used to determine the growth mode at various temperatures. Reciprocal space mapping was used to study the crystal quality of the SrTiO 3 films. It was shown that the film growth mode is governed by the energy barrier of removing unit cells from the edges of islands, which nucleate on the surface during pulsed laser deposition.

Epitaxial ZnO thin films were prepared on atomically flat sapphire (alpha-Al2O3) (0001) substrates at various substrate temperatures by laser molecular beam epitaxy. Crystal structure was analyzed by four-circle X-ray diffraction. Atomic force microscope (AFM) and reflection high energy electron diffraction (RHEED) were used to evaluate surface morphology. When ZnO was deposited on atomically flat sapphire (0001), an epitaxial ZnO film was grown with c-axis orientation, having two different in-plane orientation, ZnO [1010] \\ sapphire [1010] (400-450 degrees C) and ZnO [1010] \\ sapphire [1120] (800-835 degrees C), depending on deposition temperature. The detailed observation of the initial growth of ZnO film deposited at 835 degrees C revealed that the growth mode followed Stranski-Krastanov growth mechanism.

We have developed a modified single-stage differentially pumped RHEED system for in situ monitoring of oxide epitaxial growth at high oxygen pressure. This modification enables us to operate the RHEED system up to oxygen pressure of 100 mTorr. RHEED intensity oscillations indicative of the layer-by-layer growth were clearly observed during LaNiO 3 epitaxial growth at 30 mTorr of pure oxygen ambient. LaNiO 3 epitaxial thin films showed both atomically flat surfaces and low resistivity, suggesting that the operative oxygen pressure was high enough to epitaxially grow oxide films under optimum conditions.

Planar type metal/insulator/metal structures composed of an epitaxial perovskite manganese oxide layer and various metal electrodes were prepared for electric-field-induced resistance switching. Only the electrode pairs including Al show good resistance switching and the switching ratio reaches its maximum of 1000. This resistance switching occurs around the interface between Al electrodes and epitaxial perovskite manganese oxide thin films.

We have performed an in situ photoemission study of Pr 1 - x Ca x MnO 3 thin films grown on LaAlO 3 (0 0 1) by laser molecular beam epitaxy. By utilizing Mn 2 p → 3 d resonant photoemission, we obtained the Mn 3d partial density of states. There was no density of states at the Fermi level, consistent with the insulating behavior of this material. Chemical potential pinning, which was observed in bulk samples, was not observed in the present study, consistent with the suppression of charge ordering under the compressive strain from the substrate.

We have performed an in situ angle-resolved photoemission spectroscopy (ARPES) on single-crystal surfaces of La 0.6 Sr 0.4 MnO 3 (LSMO) thin films to investigate the electronic structure near the Fermi level ( E F ). ARPES spectra near E F reveal the existence of a dispersive Mn-3d derived conduction band indicative of an electron pocket centered at the Γ point. Comparing the experimental band structure with the local density approximation + U band-structure calculation, the estimated size of the Fermi surface is consistent with the prediction of the calculation, while the measured bandwidth is significantly narrower than the calculation. The discrepancy between the two suggests that the renormalization effect is significant due to the strong electron correlation in LSMO.

We have studied the surface dynamics of SrTiO3 during wet etching and during subsequent high-temperature annealing. Real-time observation of the wet etching process by atomic force microscopy has made it possible to find optimal etching conditions which yield atomically smooth surfaces while avoiding the generation of etch pits. Comparison of the experimental etching rates and Monte Carlo simulations of the etching process showed that etching proceeds at different speeds depending on the local atomic-scale configuration. Similar local unit cell configuration-dependent effects influence the STO step edge dynamics during high-temperature annealing which is required to produce substrates with straight step edges and atomically smooth terraces. The combination of etching and annealing of SrTiO3 gave us an ideal substrate surface for the fabrication of Josephson tunnel junctions through atomically controlled epitaxy.

We have used high-temperature scanning tunneling microscopy (STM) to study in real time SrTiO3 step edge dynamics in the 600 degrees C to 800 degrees C temperature range. We observed a dramatic transformation of the step edge structure above 690 degrees C, involving step edge straightening due to rapid migration of surface atoms. The STM study shows that if a NH4F-HF-etched substrate is annealed at 800 degrees C, a well-ordered surface, suitable for high-T-c superconductor thin film deposition, can be produced.

Single-phase samples of LaBa 2 Fe 3 O 8+ w with −0.20≤ w ≤0.83 were synthesized, characterized by oxygen-content analyses, powder X-ray diffraction, and magnetic susceptibility, and investigated using 57 Fe Mossbauer spectroscopy. At 296 K, antiferromagnetic ordering of the Fe sites was observed for samples having w ≤0.45. When w ≤0.0, the iron atoms occupy predominantly an Fe 3+ , S =5/2 state, the rest being Fe 2+ , S =2. For w ≈0, the intensities of the components in the Mossbauer spectra correspond to random distribution of oxygen vacancies around Fe 3+ . When 0≤ w ≤0.45, increasing amounts of iron atoms enter the Fe 4+ , S =2 state. For w ≥0.45, which takes the paramagnetic state at room temperature, the amount of Fe 4+ increases accordingly. At 85 K, there is inconclusive evidence of disproportionation of Fe 4+ into Fe 3+ and Fe 5+ in the most oxidized w =0.83 sample. The room-temperature Mossbauer data show that there occurs a gradual conversion from AF to P states with increasing w up to w ≥0.45, when all AF components simultaneously disappear. This gradual frustration of the cooperative order has three contributing factors. First, an increasing proportion of the iron moments simply becomes paramagnetic in the AF arrangement. Second, the AF interactions become weakened upon disorder. Third, the AF interaction is obviously weakened by replacement of S =5/2 with S =2. The room-temperature relationship between the average internal magnetic field and the oxygen content parameter w resembles the magnetic field vs temperature relationship for a cooperative magnetic material. The common mechanism is that both temperature and oxygen loading affect the ordered spin system.

Essentially single-phase samples of Pb 2 CuSr 2 [Eu 1− x Ca x ]Cu 2 O 8+δ have been investigated in a compositional range of x = 0.0–0.3. Annealing characteristics in oxygen and nitrogen atmospheres were systematically monitored by thermogravimetric measurements. Activation energies were determined for both the oxygen uptake and loss processes. The effect of Ca doping on the critical temperature was studied, and the T c was found to be quite independent of the Ca content. The highest value of T c = 74 K was measured for the sample of x = 0.25. The hyperfine parameters of the Eu site were determined by 151 Eu Mossbauer spectroscopy. The asymmetry parameter η of the electric field gradient showed a clear dependence on both x and δ .

In order to clarify the intrinsic bulk electronic structure of La1−xSrxMnO3 (LSMO) thin films, we have performed high-energy ( h ν = 5.95 keV) synchrotron photoemission spectroscopy (PES) of Mn 2p core-levels. In sharp contrast with the previous soft X-ray PES ( h ν = 800 –1486.6 eV), the high-energy PES spectra exhibit a clear additional peak at the low binding-energy side of the Mn 2 p 3 / 2 peak. To check for surface sensitivity, we measured take-off-angle dependence of Mn 2p core-levels. The results indicate that this additional peak originates from the bulk electronic structure. The peak shows a noticeable increase in the metallic phase of LSMO for x = 0.2 and 0.4, indicating that the origin of this peak is strongly related to the metallic physical properties of LSMO thin films. A single ion ( MO 6 ) cluster calculation including charge transfer from doping-induced states reproduces the new bulk-derived feature observed in Mn 2p core-levels.

We have investigated the electronic structure of a La 0.6 Sr 0.4 FeO 3 (LSFO)/La 0.6 Sr 0.4 MnO 3 (LSMO) heterointerface using Mn 2p-3d resonant photoemission spectroscopy and X-ray absorption spectroscopy. We have found that the spectral intensity of e g↑ states near the Fermi level is gradually reduced with increasing LSFO overlayer thickness. The spectral behavior is quite similar to that of hole-doped LSMO films, indicating hole-doping in LSMO layers. We have also found that Fe 2p X-ray absorption spectrum of a LSMO/LSFO/LSMO trilayer shows the spectral evidence for electron doping in the corresponding LSFO layer. These results indicate the occurrence of charge transfer at interfaces between LSMO and LSFO layers.

Superconducting powders with the composition of (Y 1− x Eu x )Ba 2 (Cu 1− y Fe y ) 4 O 8 have been prepared by a simple sol-gel method at an oxygen pressure of 1 atm starting from an aqueous mixture of the metal acetates. Homogeneous gels were achieved by complexing copper ions by tartaric acid before the gelation process. Thermal decomposition of the gels was studied by thermogravimetry and evolved gas analysis. Single-phase bulk samples were obtained after annealing at 780 °C for 40 h. Studies on the (Y 1− x Eu x )Ba 2 Cu 4 O 8 system confirmed that yttrium may be replaced by europium within the whole substitutional range ( x = 0.0–1.0). The lattice volume was expanded while the T c was slightly decreased with the increasing europium content x . On the other hand, doping with iron both destabilizes the YBa 2 Cu 4 O 8 phase and has a strong effect on its properties even at very low concentrations ( y = 0.01–0.05). Besides the XRD and SQUID measurements the samples were characterized by thermal analysis for the oxygen stability and by Mossbauer spectroscopy for the hyperfine interactions around the Eu and Fe dopant ions.

An inexpensive EGA system, based on a quadrupole MS and a standard PC, has been constructed and connected to a commercial thermobalance via a heated capillary. The system has been tested with various inorganic compounds including CaC 2 O 4 · H 2 O, CuSO 4 · 5H 2 O, Cu(NH 3 ) 4 SO 4 · H 2 O and [Pt(NH 3 ) 5 OH]CI 3 · H 2 O. The applicability of the TG-EGA-MS system is discussed.

We present the experimental details of observing the influence of NMR transitions between sublevels of Zeeman split nuclear states on Mossbauer spectra of FeNi alloys. Magnetically soft FeNi foils were subjected to radio-frequency (rf) magnetic fields and 57 Fe Mossbauer spectra were recorded. Splitting of Mossbauer resonance lines was observed when the frequency of the external transverse rf magnetic field was close to the resonance frequency of either the ground or the excited state. We discuss the possible reasons why a well-resolved line splitting has not been previously observed in earlier works.

We have measured physical properties of Pr 1− x Ca x MnO 3 (PCMO) epitaxial thin films with different hole concentrations ( x =0.2, 0.3, 0.4, and 0.5) grown on LaAlO 3 (1 0 0) substrates by laser molecular beam epitaxy technique. The temperature dependence of the resistivity shows insulating behavior in all temperature regions and the resistivity itself monotonously decreases as x increases. This insulating nature of PCMO films is similar to that of bulk PCMO crystals. However, we did not find any indication of the resistivity anomaly associated with the onset of charge ordering irrespective of x . These results suggest that the compressive strain strongly suppresses charge-ordered states in PCMO.

We have performed an in situ resonant photoemission (RPES) study on well-ordered surfaces of La 0.6 Sr 0.4 MnO 3 thin films grown by laser molecular beam epitaxy. In sharp contrast with the previous photoemission results, the RPES spectra exhibit clear evidence of a Fermi cutoff. This result suggests that the importance of in situ photoemission measurement on well-ordered surfaces of transition metal oxides for revealing their intrinsic electronic structures.

We have performed in situ synchrotron-radiation angle-resolved photoemission (ARPES) study on well-ordered single-crystal surfaces of La 1− x Sr x MnO 3 (LSMO) thin films grown by laser molecular beam epitaxy (laser MBE). Obtained band structure of LSMO thin film consists of several highly dispersive O 2p-derived bands at the binding energies of 2.3– 7.0 eV and almost dispersionless Mn 3d-derived structures near the Fermi level. The present study has demonstrated that in situ ARPES on transition metal oxide thin films grown by laser MBE is a capable experimental technique to determine the band structure of three dimensional transition metal oxides.