Search results for " Electron"
showing 10 items of 12924 documents
Custom measurement system for memristor characterisation
2021
Abstract A cheap, compact and customisable characterisation system for memristor devices, working between ± 10 V, is presented. SPICE (Simulation Program with Integrated Circuit Emphasis) simulations are performed to verify the circuit feasibility and a proper software is developed to drive the system. The potentiality of the realised system is tested by performing several electrical measurements on both Cu/HfO2/Pt memristors and two-terminals commercial devices.
A General Mathematical Formulation for the Determination of Differential Leakage Factors in Electrical Machines with Symmetrical and Asymmetrical Ful…
2018
This paper presents a simple and general mathematical formulation for the determination of the differential leakage factor for both symmetrical and asymmetrical full and dead-coil windings of electrical machines. The method can be applied to all multiphase windings and considers Gorges polygons in conjunction with masses geometry in order to find an easy and affordable way to compute the differential leakage factor, avoiding the adoption of traditional methods that refer to the Ossanna's infinite series, which has to be obviously truncated under the bound of a predetermined accuracy. Moreover, the method described in this paper allows the easy determination of both the minimum and maximum v…
Piecewise Affine (PWA) Modeling and Switched Damping Control of Two-Inertia Systems with Backlash
2018
Backlash degrades positioning accuracy and can induce mechanical wear and breakage by collisions. Therefore, a lot of studies have been conducted on backlash compensation. The simplest control method for the impact attenuation is torsional damping addition by feedback of torsional velocity. This paper reveals the advantages and disadvantages of the torsional damping addition. Based on the analyses, a novel switched damping control is proposed to realize the responses with smaller overshoot while attenuating the impact. The mechanical system and the proposed controller are described as piecewise affine systems for analyses. The performance of the proposed method is compared with a linear dam…
Magnetic domain structure of La0.7Sr0.3MnO 3 thin-films probed at variable temperature with scanning electron microscopy with polarization analysis
2013
The domain configuration of 50 nm thick La0.7Sr0.3MnO3 films has been directly investigated using scanning electron microscopy with polarization analysis (SEMPA), with magnetic contrast obtained without the requirement for prior surface preparation. The large scale domain structure reflects a primarily four-fold anisotropy, with a small uniaxial component, consistent with magneto-optic Kerr effect measurements. We also determine the domain transition profile and find it to be in agreement with previous estimates of the domain wall width in this material. The temperature dependence of the image contrast is investigated and compared to superconducting-quantum interference device magnetometry …
Spin Hall magnetoresistance in antiferromagnetic insulators
2020
Antiferromagnetic materials promise improved performance for spintronic applications, as they are robust against external magnetic field perturbations and allow for faster magnetization dynamics compared to ferromagnets. The direct observation of the antiferromagnetic state, however, is challenging due to the absence of a macroscopic magnetization. Here, we show that the spin Hall magnetoresistance (SMR) is a versatile tool to probe the antiferromagnetic spin structure via simple electrical transport experiments by investigating the easy-plane antiferromagnetic insulators $\alpha$-Fe2O3 (hematite) and NiO in bilayer heterostructures with a Pt heavy metal top electrode. While rotating an ext…
An insulating doped antiferromagnet with low magnetic symmetry as a room temperature spin conduit
2020
We report room temperature long-distance spin transport of magnons in antiferromagnetic thin film hematite doped with Zn. The additional dopants significantly alter the magnetic anisotropies, resulting in a complex equilibrium spin structure that is capable of efficiently transporting spin angular momentum at room temperature without the need for a well-defined, pure easy-axis or easy-plane anisotropy. We find intrinsic magnon spin-diffusion lengths of up to 1.5 {\mu}m, and magnetic domain governed decay lengths of 175 nm for the low frequency magnons, through electrical transport measurements demonstrating that the introduction of non-magnetic dopants does not strongly reduce the transport…
Large Zero-Field Cooled Exchange-Bias in BulkMn2PtGa
2013
We report a large exchange-bias (EB) effect after zero-field cooling the new tetragonal Heusler compound Mn2PtGa from the paramagnetic state. The first-principle calculation and the magnetic measurements reveal that Mn2PtGa orders ferrimagnetically with some ferromagnetic (FM) inclusions. We show that ferrimagnetic (FI) ordering is essential to isothermally induce the exchange anisotropy needed for the zero-field cooled (ZFC) EB during the virgin magnetization process. The complex magnetic behavior at low temperatures is characterized by the coexistence of a field induced irreversible magnetic behavior and a spin-glass-like phase. The field induced irreversibility originates from an unusual…
Effective strain manipulation of the antiferromagnetic state of polycrystalline NiO
2021
As a candidate material for applications such as magnetic memory, polycrystalline antiferromagnets offer the same robustness to external magnetic fields, THz spin dynamics, and lack of stray field as their single crystalline counterparts, but without the limitation of epitaxial growth and lattice matched substrates. Here, we first report the detection of the average Neel vector orientiation in polycrystalline NiO via spin Hall magnetoresistance (SMR). Secondly, by applying strain through a piezo-electric substrate, we reduce the critical magnetic field required to reach a saturation of the SMR signal, indicating a change of the anisotropy. Our results are consistent with polycrystalline NiO…
Maximum Torque Per Ampere control algorithm for low saliency ratio interior permanent magnet synchronous motors
2017
This paper presents an investigation on the comparison between the Maximum Torque Per Ampere (MTPA) and the Field Orientation Control (FOC) algorithms for interior permanent magnet synchronous machines (IPMSMs). In particular, this study was carried out on a small-power IPMSM with low salience ratio. Both control algorithms have been implemented in the Matlab/Simulink environment, obtaining promising results.
Pulsed Electro-Acoustic Method for specimens and cables employed in HVDC systems: Some feasibility considerations
2018
Recent experiments on the use of the PEA method for testing dielectric materials in specimens and comparison with a detailed model provide an insight of the phenomenon and suggest the need of adopting similar models also for cables. What is said is even more important considering the possible future adoption of the PEA methodology to test DC cables for Pre-Qualification and Type Tests. The use of an accurate model of the PEA cell used for testing specimens and related experiments prove that the thickness of the different parts composing the PEA setup is a basic element for providing accurate charge reading and interpretation of the phenomenon. Both simulation and experimental results, carri…