2,601 research outputs found
Low frequency noise due to magnetic inhomogeneities in submicron FeCoB/MgO/FeCoB magnetic tunnel junctions
We report on room temperature low frequency noise due to magnetic
inhomogeneities/domain walls (MI/DWs) in elliptic submicron FeCoB/MgO/FeCoB
magnetic tunnel junctions with an area between 0.0245 and 0.0675{\mu}m2. In the
smaller area junctions we found an unexpected random telegraph noise (RTN1),
deeply in the parallel state, possibly due to stray field induced MI/DWs in the
hard layer. The second noise source (RTN2) is observed in the antiparallel
state for the largest junctions. Strong asymmetry of RTN2 and of related
resistance steps with current indicate spin torque acting on the MI/DWs in the
soft layer at current densities below 5x10^5 A/cm2.Comment: 12 pages, 4 figure
Respective influence of in-plane and out-of-plane spin-transfer torques in magnetization switching of perpendicular magnetic tunnel junctions
The relative contributions of in-plane (damping-like) and out-of-plane
(field-like) spin-transfer-torques in the magnetization switching of
out-of-plane magnetized magnetic tunnel junctions (pMTJ) has been theoretically
analyzed using the transformed Landau-Lifshitz (LL) equation with the STT
terms. It is demonstrated that in a pMTJ structure obeying macrospin dynamics,
the out-of-plane torque influences the precession frequency but it does not
contribute significantly to the STT switching process (in particular to the
switching time and switching current density), which is mostly determined by
the in-plane STT contribution. This conclusion is confirmed by finite
temperature and finite writing pulse macrospin simulations of the current-field
switching diagrams. It contrasts with the case of STT-switching in in-plane
magnetized MTJ in which the field-like term also influences the switching
critical current. This theoretical analysis was successfully applied to the
interpretation of voltage-field STT switching diagrams experimentally measured
on perpendicular MTJ pillars 36 nm in diameter, which exhibit macrospin-like
behavior. The physical nonequivalence of Landau and Gilbert dissipation terms
in presence of STT-induced dynamics is also discussed
Manipulating the Voltage Dependence of Tunneling Spin Torques
Voltage-driven spin transfer torques in magnetic tunnel junctions provide an
outstanding tool to design advanced spin-based devices for memory and
reprogrammable logic applications. The non-linear voltage dependence of the
torque has a direct impact on current-driven magnetization dynamics and on
devices performances. After a brief overview of the progress made to date in
the theoretical description of the spin torque in tunnel junctions, I present
different ways to alter and control the bias dependence of both components of
the spin torque. Engineering the junction (barrier and electrodes) structural
asymmetries or controlling the spin accumulation profile in the free layer
offer promising tools to design efficient spin devices.Comment: 10 pages, 4 figures, SPIE conference proceeding
Effects of Low Concentration of Selected Analgesics and Successive Bioaugmentation of the Activated Sludge on Its Activity and Metabolic Diversity
In this study, we evaluated the impact of the successive bioaugmentation of the activated
sludge (AS) with the defined bacterial consortium on the activity and functional capacity of the
AS microorganisms. In parallel, the removal of low concentrations of the selected non-steroidal
anti-inflammatory drugs (ibuprofen, naproxen, diclofenac) and analgesic paracetamol was studied.
We found that the addition of the bacterial consortium consisting of three pharmaceuticals-degrading
strains Bacillus thuringiensis B1 (2015b), Stenotrophomonas maltophilia KB2, and Pseudomonas moorei
KB4 into the AS did not cause any significant changes in the biomass abundance and metabolic
activity of the AS microorganisms. Although, the successive bioaugmentation of the AS caused a
slight increase in the metabolic diversity, the intensity of carbohydrates usage, and metabolic richness.
Microorganisms in the bioaugmented and non-bioaugmented AS were able to degrade the mixture of
the analyzed drugs with similar e ciency, however, diclofenac was removed more e ectively in the
bioaugmented AS. Several metabolites were identified and e ciently utilized, with the exception of
4-OH diclofenac. Two new diclofenac-degrading strains assigned as Serratia proteamaculans AS4 and
Rahnella bruchi AS7 were isolated from the diclofenac-treated AS
Randomness on the Lattice
In this lecture we review recent lattice QCD studies of the statistical
properties of the eigenvalues of the QCD Dirac operator. We find that the
fluctuations of the smallest Dirac eigenvalues are described by chiral Random
Matrix Theories with the global symmetries of the QCD partition function.
Deviations from chiral Random Matrix Theory beyond the Thouless energy can be
understood analytically by means of partially quenched chiral perturbation
theory.Comment: Invited talk at the International Light-Cone Meeting on
Non-Perturbative QCD and Hadron Phenomenology, Heidelberg 12-17 June 2000. 12
pages, 7 figures, Late
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