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Large (up to 100 μm long), loosely coiled, free-living spirochetes with variable diameters (from 0.4 to 3 μm in the same cell) were seen at least 40 times between August 1990 and January 1993. These spirochetes were observed in mud water and enrichment media from highly specific habitats in intertidal evaporite flats at three disjunct localities, one in(More)
We report the experimental observation of sub-Poissonian shot noise in single magnetic tunnel junctions, indicating the importance of tunneling via impurity levels inside the tunnel barrier. For junctions with weak zero-bias anomaly in conductance, the Fano factor (normalized shot noise) depends on the magnetic configuration being enhanced for antiparallel(More)
We have studied the magnetic hysteresis cycle of La0.67Sr0.33MnO3/SrRuO3 antiferromagnetically coupled bilayers, by magnetometry and polarized neutron reflectometry. A positive exchange bias as well as an unusual asymmetry are observed on the magnetic reversal process of the La0.67Sr0.33MnO3 layer. Through an extended Stoner-Wohlfarth model comprising the(More)
To order the complete compilation report, use: ADA418228 The component part is provided here to allow users access to individually authored sections)f proceedings, annals, symposia, etc. However, the component should be considered within [he context of the overall compilation report and not as a stand-alone technical report. We have studied the low(More)
Abstract The time dependences, up to 200 s, and the noise power spectrum (0.005–10 Hz) in the electron transport response at bias up to 300 mV of Co/Al2O3/Ni80Fe20 magnetic tunnel junctions (MTJs) and of Co/Al2O3〈δ(Fe)〉/Ni80Fe20 (with Fe δ dopants of thickness 1.8 Å inside the barrier) were investigated. The magnetic field was changed between +100 and −100(More)
Citation Guerrero, R. et al. "Conductance in Co/Al2O3/Si/Al2O3 permalloy with asymmetrically doped barrier. Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access(More)
We report on the strong in uence of carbon doping on 1/f noise in fully epitaxial Fe/MgO(100) 12 ML/Fe magnetic tunnel junctions in comparison with undoped junctions with a large density of barrier defects. Carbon in uences the relaxation of defects, the reconstruction of the interface and the symmetry transformation of interface resonance states, which are(More)
Fully epitaxial Fe͑110͒/MgO͑111͒/Fe͑110͒ magnetic tunnel junctions ͑MTJs͒ have been tested with respect to symmetry-enforced spin filtering. The Fe͑110͒ electrodes exhibit ⌺ 1↑ and ⌺ 1↓ spin states, both crossing the Fermi level, but with a group velocity about 50% smaller for the minority states compared to the majority ones. These epitaxial but(More)
We investigate current-driven magnetization dynamics in synthetic Fe /Cr 10 multilayer antiferromagnets by using low-frequency voltage noise measurements. We observe suppression of the noise above a critical current density of about 2 105 A /cm2. Theoretical estimates suggest that this effect may be attributed to currentinduced motion of domain walls in the(More)