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Magnetic tunnel junctions with a ferrimagnetic barrier layer have been studied to understand the role of the barrier layer in the tunneling process -a factor that has been largely overlooked until recently. Epitaxial oxide junctions of highly spin polarized La 0.7 Sr 0.3 MnO 3 and Fe 3 O 4 electrodes with magnetic NiMn 2 O 4 (NMO) insulating barrier layers provide a magnetic tunnel junction system in which we can probe the effect of the barrier by comparing junction behavior above and below the Curie temperature of the barrier layer. When the barrier is paramagnetic, the spin polarized transport is dominated by interface scattering and surface spin waves; however, when the barrier is ferrimagnetic, spin flip scattering due to spin waves within the NMO barrier dominates the transport. 72.25.Mk,75.70.Cn

A comprehensive study was performed to quantify the risk of burns from hot beverage spills. The study was comprised of three parts. First, experiments were carried out to measure the cooling rates of beverages in a room-temperature environment by natural convection and thermal radiation. The experiments accounted for different beverage volumes, initial temperatures, cooling period between the time of service and the spill, the material which comprised the cup, the presence or absence of a cap and the presence or absence of an insulating corrugated paper sleeve. Among this list, the parameters which most influenced the temperature variation was the presence or absence of a cover or cap, the volume of the beverage and the duration of the cooling period. The second step was a series of experiments that provided temperatures at the surface of skin or skin surrogate after a spill. The experiments incorporated a single layer of cotton clothing and the exposure duration was 30 s. The outcomes of the experiments were used as input to a numerical model which calculated the temperature distribution and burn depth within tissue. Last was the implementation of the numerical model and a catalogue of burn predictions for various beverage volumes, beverage service temperatures, and durations between beverage service and spill. It is hoped that this catalogue can be used by both beverage industries and consumers to reduce the threat of burn injuries. It can also be used by treating medical professionals who can quickly estimate burn depths following a spill incident.

Epitaxial magnetic tunnel junctions with electrodes of spinel-structure Fe3O4 and perovskite La0.7Sr0.3MnO3 have been fabricated and characterized. Spinel barrier layers of magnetic FeGa2O4 and nominally nonmagnetic Mg2TiO4 were used to provide a good interface with the more sensitive Fe3O4 electrode interface. Junction magnetoresistances (JMRs) of up to −11% at 60K and −26% at 70K were observed for FeGa2O4 and Mg2TiO4 barrier junctions, respectively. The JMR bias dependence and junction resistance versus temperature data indicate that a majority of the junctions are dominated by elastic tunneling below about 50mV and by inelastic hopping through the barrier at higher bias.

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