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In this work, we use ultrafast optical pump-optical probe spectroscopy to probe the polaron dynamics in La0.7Ca0.3MnO3 (LCMO) thin films. The temporal evolution in transient reflectivity change ΔR/R exhibits two relaxing components: a fast component with a time constant of subpicosecond and a slow component with time constant ranging from tens of picoseconds to hundreds of picoseconds. The amplitude of the fast component, though has been seldom discussed before, exhibits the similar temperature dependence with that of the resistivity and the neutron scattering intensity due to nanoscale correlated polarons. The results strongly suggest that the fast photoinduced reflectivity change may have been due to the photoexcitation and trapping process of correlated Jahn–Teller polarons in the paramagnetic and ferromagnetic phases and, thus, implies the presence of electronic inhomogeneity in LCMO manganites. [ABSTRACT FROM AUTHOR]

Magneto-optical Kerr effect, low-energy electron diffraction, and Auger electron spectroscopy were used to investigate the magnetic properties and the growth mode of ultrathin Co films deposited on 1 ML (monolayer) Ni/Pt(111) at room temperature. No Kerr signal was observed when the thickness of Co film was below 3 ML, and the easy axis of the magnetization was in plane when the thickness of Co was greater than 3 ML at room temperature. The polar Kerr signal appeared after the sample was annealed at 450 K for 1 ML of Co. Further studies in the magnetic properties and surface composition of 3 ML Co/1 ML Ni/Pt(111) during an annealing process showed that the out-of-plane magnetization enhances significantly when Co and Ni atoms diffuse into the Pt substrate. The coercivity of the system can be adjusted by changing the annealing temperature. Measuring at room temperature, the coercivity increases when the annealing temperature rises. The possible mechanism of the evolution of magnetic properties with the structure of the interface is discussed. [ABSTRACT FROM AUTHOR]

The epitaxial growth and alloy formation of Ag-capped layer on Ni/Pt(111) surface were investigated using Auger electron spectroscopy, ultraviolet photoelectron spectroscopy, and low-energy electron diffraction. The growth of Ag on one ML Ni/Pt(111) transforms from layer-by-layer mode into three-dimensional island mode after the growth of one atomic monolayer of Ag. The starting temperature for the alloy formation of Ni–Pt is dependent of the thickness of Ni films. The interface compositions after the high-temperature annealing were studied with the depth-profile analysis of Ar ion sputtering. [ABSTRACT FROM AUTHOR]

Presents a study that investigated the effects of doping on the microstructural and magnetic properties of barium ferrite thin films when chromium oxide or yttrium oxide were used as the dopants. Details of the experiment; Results; Discussion and conclusions.

We study thin films and magnetic tunnel junction nanopillars based on Ta/Co20Fe60B20/MgO multilayers by electrical transport and magnetometry measurements. These measurements suggest that an ultrathin magnetic oxide layer forms at the Co20Fe60B20/MgO interface. At approximately 160 K, the oxide undergoes a phase transition from an insulating antiferromagnet at low temperatures to a conductive weak ferromagnet at high temperatures. This interfacial magnetic oxide is expected to have significant impact on the magnetic properties of CoFeB-based multilayers used in spin torque memories. [ABSTRACT FROM AUTHOR]

The effects of plasma treatment of textured substrates on orientation ratio (OR) as well as in-plane Cr(200)/Co(11.0) preferred orientation (PO) and coercivity (Hc) in longitudinal magnetic recording media have been systematically investigated. OR is found to increase by ~0.2-0.3 with enhanced PO and Hc for samples with slightly rf sputter etched substrates. Further Ar+ plasma dry etching (higher power/longer duration) leads to a slow decrease of OR to =1, then a worsened/vanishing PO and finally a drastic drop in Hc. The origin of OR is primarily attributed to stress effects (of most importance being the anisotropic stress induced preferential easy axis distribution), with anisotropic topography and PO as two necessary preconditions for OR>1. Ion beam bombardment induced chemical/structural modifications and residual stress in the substrate surface layer may play important roles in film growth/structures/properties and therefore in the mechanisms of the evolution of OR with plasma treatment. [ABSTRACT FROM AUTHOR]

Thin film transistors are fabricated by in situ growth of SnO2 nanobelts on Au/Pt electrodes. A linear correlation in the output characteristics is observed at zero gate voltage, indicating Ohmic contacts between the nanobelts and the electrodes. The transistors exhibit n-type behaviors and have a mobility of 1.85 cm2/V s with a current on/off ratio above 103. The conductance increases as the pressure in the device chamber is reduced, which indicates that the transistors are promising for oxygen detecting. [ABSTRACT FROM AUTHOR]

Photolysis of CpPt(Me)3(Cp=η5-C5H5, Me=CH3) at room temperature and atmospheric pressure produces thin films and patterned structures of platinum metal on solid substrates. The platinum films are characterized by Auger electron spectroscopy, x-ray diffraction, and scanning electron microscopy. Substrates can also be prepatterned by laser irradiation and then developed into a shiny platinum deposit at a later time. [ABSTRACT FROM AUTHOR]

Mo¨ssbauer and magnetic studies have shown that 1-2 wt % of SiO[sub 2] could be dissolved in the CoFe[sub 2]O[sub 4] structure. Changes in magnetization and Curie temperature were observed. The presence of SiO[sub 2] might enhance magnetic anisotropy. Coercivity values of up to 3.5 kOe were measured for mechanically alloyed CoFe[sub 2]O[sub 4]/SiO[sub 2] powders. High coercivities were also achieved in SiO[sub 2]-doped Co-ferrite thin films prepared by sputtering technique. The Co-ferrite thin film deposited on a silicon wafer using a 5 wt % SiO[sub 2]/Co-ferrite target possessed a coercivity of 7.4 kOe. Spring-magnet behavior was observed, indicating the possible presence of remanence enhancement due to exchange coupling because of nanocrystalline structure. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A magnetic force microscope (MFM) was used to image the topography and magnetic microstructures of Co[sub 22]Ag[sub 78] granular films. The observed morphology shows isolated nanometer-scale cobalt particles (granules) embedded in the silver matrix. Stripe magnetic domains with much larger size (typically of ∼100 nm wide) than that of cobalt particles are resolved clearly on MFM micrographs for the annealed samples. It is demonstrated that the domain width and the relative magnetic force strength first increases and then decreases with annealing temperature with a maximum at about 600 K. We suggest that the appearance of the stripe domains is attributed to magnetic correlation among many of the isolated single-domain cobalt particles and is dependent on the microstructure of the samples. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]

CIGS film was formed using one-step electrochemical deposition at various deposition potential voltages in solution with diverse pH values. Multiple material analyses such as X-ray diffraction (XRD) analysis, scanning electron microscope (SEM) images, energy dispersive spectroscopy (EDS), and electron probe micro-analyzer (EPMA) images were used to examine the electro-deposition parameters. UV spectrometer was performed to measure the bandgap of the CIGS thin film. A highest Ga composition could be obtained at the most negative voltage of -3.3V and the smallest pH value of 1.6 in our experiment. However, an inferior material property and worse crystalline phase might come with a high Ga concentration. The band gap of the electro-deposited CIGS film with Cu:In:Ga:Se ratio of 1:0.52:0.30:1.98 could achieve 1.16 eV. The electrodeposited CIGS film shows promises for future solar cell applications. [ABSTRACT FROM AUTHOR]