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GaAs-based spin LEDs were used to study spin injection through a Schottky barrier from a ferromagnetic contact formed by an in-situ technique. Optical measurements were performed in both oblique Hanle and Faraday geometry. In addition to direct recombination at the r-point in the quantum well, emission peaks were seen due to phonon-assisted recombination from the X and L valleys in the semiconductor. The presence of the phonon replica peaks indicates that strong tunneling occurs from the Fe into the X and L minima at the interface. As measured in the oblique Hanle geometry, the satellite peaks display optical polarization, which indicates spin polarized injection into these minima. It is argued that enhanced tunneling into the X and L minima leads to a lower spin polarization in the device due to the transport properties of these valleys. This mechanism then limits the maximum effective spin polarization that can be achieved at a coherent interface. [ABSTRACT FROM AUTHOR]

The electron spin detection efficiency was studied across Co/GaAs structures using photoexcitation techniques. Two sets of samples were prepared where the substrate surface was pretreated by annealing prior to growth for the first set whereas for the second no annealing treatment was carried out. While, in the annealed sample, spin detection was observed, the nonannealed case showed no spin-dependent transport effects. This is attributed to the absence of a Schottky tunnel barrier to facilitate tunnelling through the interface, as the transport mechanism responsible for the spin filtering. Furthermore, it illustrates the influence of the interface quality on spin dependent transport processes for the general case of any FM electrode. [ABSTRACT FROM AUTHOR]

A novel magnetic encoding technique for performing high-throughput biological assays using molecular probes such as antibodies and DNA oligonucleotides is presented. Electrodeposited Ni/Au multilayer pillar structures with diameters from 5-20 µm and thicknesses from 1-10 µm are presented as "magnetic barcodes," where the number of unique codes possible increases exponentially with a linear increase in pillar size. We have successfully functionalized these pillars using a HS-C10-NHS self-assembled monolayer (SAM) grown on the Au cap layer and attachment of an NH2 modified primer oligo sequence and have shown hybridization and denaturation to a fluorescent template. In addition we have developed a novel release layer methodology that allows a large library of probes to be inkjet printed on a single 5 mm² chip prior to release. [ABSTRACT FROM AUTHOR]

We demonstrate the use of an exchange-biased magnetic multilayer structure as a promising basis for developing a three-dimensional-patterned storage medium. The behavior of several multilayered structures is investigated. The structures are of the form Si(001)/Ta/Co/Ta/Co/FeMn/Ta/Co/FeMn/Ta. The memory state is determined by the orientation of the magnetization of each magnetic layer. In order to achieve the independent switching of the magnetic layers necessary to set the state of the three-dimensional (3-D) ‘memory,’ the switching field and coercivity are controlled by making use of the increased coercivity and exchange biasing that result from coupling an antiferromagnetic layer to a ferromagnetic layer, and by varying the thickness of each magnetic layer. The change in behavior upon patterning the exchange-biased continuous multilayered films into arrays of 50-μm diameter dots, is investigated. We find that patterning on this scale dramatically changed the switching behavior of the magnetic layers. [ABSTRACT FROM AUTHOR]

We present magnetometry data for a range of Fe thicknesses grown on GaAs and InAs substrates in order to determine the factors governing the evolution of the magnetic moment of epitaxial Fe grown on a zinc-blende semiconductor. Fe films grown at room temperature by molecular beam epitaxy were characterized structurally and magnetically. The estimated roughness amplitudes were 0.3 ± 0.2 nm for the Fe/GaAs interface and 0.6 ± 0.2 nm for Fe/InAs. We observe a greater reduction of the Fe magnetic moment for films grown on InAs as compared to GaAs, as the Fe films reach a bulk-like moment (within 10% deviation) at a thickness of ∼5.2 nm and ∼2.2 mn, respectively. We conclude that the growth conditions, in particular interface and interdiffusion effects, are the dominant mechanisms influencing the value of the magnetic moment for ultrathin Fe films on GaAs and InAs. [ABSTRACT FROM AUTHOR]

Presents a study that examined the growth and interface magnetic properties of epitaxial iron films grown on indium arsenide. Analysis of the low-energy diffraction patterns of the thin film; Determination of the x-ray absorption spectra; Evaluation of the spin moments of the thin film.

Focuses on the size dependence of the magnetization reversal process in micron size magnetic iron/gallium arsenic (Fe/GaAs)(001) microstripes. Information on the switching process in the Fe/GaAs(001) thin films; Fabrication of the microstripes; Measurements of ex-situ magneto-optic Kerr effect (MOKE).

Investigates the use of magneto-optic Kerr effect in-situ to the effects of exposing ultrathin cobalt/copper(100) (Co/Cu) films to carbon monoxide gas and the subsequent effects of depositing submonolayer quantities of Cu. Effect of nonmagnetic adsorbates on ultrathin ferromagnetic films; Information on the effect of depositing submonolayer incremental coverages of Cu on to Co/Cu(110) films.

Presents a study which described the structural and magnetic properties of tauMnAl/Co superlattices epitaxially grown on alas/GaAs by Molecular Beam Epitaxy. Experimental details; Results of the study; Conclusions.