Search results for "Hall Effect"
showing 10 items of 702 documents
Magnetic Anisotropies and Coupling Mechanisms inFe/Mo(110)Nanostripes
2005
Using low-temperature (5 K) spin-polarized scanning tunneling microscopy, we have studied the morphology and magnetic properties of monolayer (ML) and double layer (DL) thick Fe nanowires grown by step flow on a Mo(110) single crystal. Magnetic contrast has been obtained using tungsten tips covered by Au/Co thin films. We find that the DL Fe nanowires, similarly to ML Fe nanowires, are perpendicularly magnetized. Because of the dipolar coupling, separated DL Fe nanowires are antiferromagnetically coupled. DL wires that are touching at step edges are ferromagnetically ordered due to direct exchange coupling. We measured the widths of the magnetic domain walls in the ML and DL Fe nanowires. T…
Current-Induced Skyrmion Generation through Morphological Thermal Transitions in Chiral Ferromagnetic Heterostructures.
2018
© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Magnetic skyrmions promise breakthroughs in future memory and computing devices due to their inherent stability and small size. Their creation and current driven motion have been recently observed at room temperature, but the key mechanisms of their formation are not yet well-understood. Here it is shown that in heavy metal/ferromagnet heterostructures, pulsed currents can drive morphological transitions between labyrinth-like, stripe-like, and skyrmionic states. Using high-resolution X-ray microscopy, the spin texture evolution with temperature and magnetic field is imaged and it is demonstrated that with transient Joule heating, topologica…
Magnetotransport properties of epitaxial - and -oriented CeSb thin films
2000
Abstract We present the electronic magnetotransport properties of (1 0 0) - and (1 1 1) -oriented CeSb thin films. The samples were grown epitaxially by molecular beam epitaxy onto sapphire (1 1 2 0) and (0 0 0 1) substrates. The temperature-dependent resistivity is in full correspondence with the behaviour known from bulk material. For (1 0 0) -oriented films the analysis of the temperature and magnetic field-dependent magnetoresistivity results in a H/T phase diagram analogous to that of bulk samples. For (1 1 1) -oriented films slight deviations were observed. In Hall-effect measurements of (1 0 0) -oriented samples a sign change of the Hall coefficient occurred which is in contrast to m…
Magnetism of Co-doped ZnO thin films
2007
We have investigated magnetic and transport properties of 5% Co-doped and undoped ZnO thin films deposited on $r$ plane ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ substrates by pulsed laser deposition. The Co doped films showed paramagnetic and ferromagnetic behavior as well as a high magnetoresistance and a small anomalous Hall effect. In a range of $0\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}5\phantom{\rule{0.3em}{0ex}}\mathrm{T}$ at low temperatures we observed a double sign change of the magnetoresistance. For undoped ZnO films, prepared by the same conditions, only a negative MR was observed, but surprisingly also a very small anomalous Hall effect. We explain our results…
Spin Hall magnetoresistance in the non-collinear ferrimagnet GdIG close to the compensation temperature
2017
We investigate the spin Hall magnetoresistance (SMR) in a gadolinium iron garnet (GdIG)/platinum (Pt) heterostructure by angular dependent magnetoresistance measurements. The magnetic structure of the ferromagnetic insulator GdIG is non-collinear near the compensation temperature, while it is collinear far from the compensation temperature. In the collinear regime, the SMR signal in GdIG is consistent with the usual [Formula: see text] relation well established in the collinear magnet yttrium iron garnet, with [Formula: see text] the angle between magnetization and spin Hall spin polarization direction. In the non-collinear regime, both an SMR signal with inverted sign and a more complex an…
Growth mechanism and transport properties of thin La0.67Ca0.33MnO3 films
1999
Abstract We prepared thin films of La 0.67 Ca 0.33 MnO 3 on different substrates with DC sputtering. The measured transport and magnetic properties could be explained by a lattice mismatch induced by the substrate. Hall effect measurements showed a holelike charge carrier density n * h = 1.3 per unit cell below T C . The magnetoresistance results from an increase of the mobility of the charge carriers in magnetic field.
Wave-vector analysis of plasmon-assisted distributed nonlinear photoluminescence along Au nanowires
2020
We report a quantitative analysis of the wavevector diagram emitted by nonlinear photoluminescence generated by a tightly focused pulsed laser beam and distributed along Au nanowire via the mediation of surface plasmon polaritions. The nonlinear photoluminescence is locally excited at key locations along the nanowire in order to understand the different contributions constituting the emission pattern measured in a conjugate Fourier plane of the microscope. Polarization-resolved measurements reveal that the nanowire preferentially emits nonlinear photoluminescence polarized transverse to the long axis at close to the detection limit wavevectors with a small azimuthal spread in comparison to …
Microwave characterization and modeling of packaged HEMTs by a direct extraction procedure at cryogenic temperatures
2004
In the present work we employ a direct extraction procedure to determine small signal equivalent circuit of microwave GaAs FETs by means of scattering (S-) parameter measurements down to cryogenic temperatures. The direct extraction procedure was tested on packaged AlGaAs/InGaAs HEMTs and good agreement between the simulated and measured S-parameters was obtained at different bias and temperature conditions. We employed a properly designed cryogenic set-up operating in our laboratory that allows to perform DC and RF characterization down to 30 K.
Parameters influencing the stiffness of composites reinforced by carbon nanotubes – A numerical–analytical approach
2014
Abstract Due to their high stiffness and strength, as well as their electrical conductivity, carbon nanotubes are under intense investigation as fillers in polymer matrix composites. The nature of the carbon nanotube/polymer bonding and the curvature of the carbon nanotubes may strongly reduce the reinforcing effect of the carbon nanotubes when added to a matrix to create composites. Here the effects of carbon nanotube waviness and the interaction with the matrix on the stiffness of the composite are investigated. Using a mixed numerical–analytical model, a parametric study of the waviness and volume fraction influence of CNTs on the elastic behavior of the nanocomposite is presented. The m…
Surface plasmon subwavelength optics.
2003
International audience; Surface plasmons are waves that propagate along the surface of a conductor. By altering the structure of a metal's surface, the properties of surface plasmons- in particular their interaction with light-can be tailored, which offers the potential for developing new types of photonic device. This could lead to miniaturized photonic circuits with length scales that are much smaller than those currently achieved. Surface plasmons are being explored for their potential in subwavelength optics, data storage, light generation, microscopy and bio-photonics.