Search results for "MAGNETIC FIELD"
showing 10 items of 1488 documents
Recent developments in the manipulation of magnetic domain walls in CoFeB–MgO wires for applications to high-density nonvolatile memories
2015
Abstract The recent discovery that magnetic domain walls can be moved under a small current without any magnetic field opens a perspective for a paradigm shift in mass storage design. However, several fundamental questions must be answered before the technology can be considered feasible. This review covers the current understanding of domain wall (DW) propagation in CoFeB–MgO structures with perpendicular magnetic anisotropy. These films exhibit a very low density of pinning centers and can be integrated in Magnetic Tunnel Junctions, making them very promising for manipulating multiple domain walls in ultra-high-density spintronic devices. Several important issues are addressed: the physic…
Effect of DC Electric Field on the Emitted THz Signal of Antenna-Coupled Spintronic Emitters
2019
We study the impact of an external electric DC field on antenna-coupled spintronic THz emitters driven by a 90 fs, 1550 nm laser oscillator. Simultaneous application of external electric and magnetic field shows a quadratic decrease in peak-peak THz pulse with increase in the bias voltage. We ascribe this decrease to Joule heating caused by the DC current flowing through the spintronic material.
Transmission Attenuation Power Ratio Analysis of Flexible Electromagnetic Absorber Sheets Combined with a Metal Layer.
2018
Electromagnetic noise absorber sheets have become a solution for solving complex electromagnetic interference (EMI) problems due to their high magnetic losses. This contribution is focused on characterizing a novel structure that is based on an absorber film with a metal layer attached on its top side. Two different absorber compositions were combined with Al and Cu metal layers in order to study the improvement on the performance of these structures, depending on the complex permeability, absorber film thickness, and type of metal. The transmission attenuation power ratio of the absorber films is analyzed and compared to the performance of absorber and metal structures. The measurement pro…
High-Spatial-Resolution Monitoring of Strong Magnetic Field using Rb vapor Nanometric-Thin Cell
2011
We have implemented the so-called $\lambda$-Zeeman technique (LZT) to investigate individual hyperfine transitions between Zeeman sublevels of the Rb atoms in a strong external magnetic field $B$ in the range of $2500 - 5000$ G (recently it was established that LZT is very convenient for the range of $10 - 2500$ G). Atoms are confined in a nanometric thin cell (NTC) with the thickness $L = \lambda$, where $\lambda$ is the resonant wavelength 794 nm for Rb $D_1$ line. Narrow velocity selective optical pumping (VSOP) resonances in the transmission spectrum of the NTC are split into several components in a magnetic field with the frequency positions and transition probabilities depending on th…
A magnetostrictive sensor interrogated by fiber gratings for DC-current and temperature discrimination
2000
A magnetostrictive sensor head with temperature compensation has been developed for measurement of static magnetic fields. The device consists on two different alloys with similar thermal expansion coefficient one of which has a giant magnetostriction, the expansion of both materials produced by heat and magnetism is detected by two fiber gratings. One of the gratings measures the temperature of the sensor and the difference between the wavelengths reflected by the gratings is a measurement of the magnetically induced strain.
Magnetic Field Gradiometer with Sub-Micron Spatial Resolution Based on Caesium Vapour in an Extremely Thin Cell
2015
Abstract In this paper we present a device for measuring the magnetic field and its gradient with a spatial resolution of several hundred nanometres. This device is based on caesium metal vapour confined to an extremely thin cell (ETC). To measure magnetic signals, we use absorption and very low laser powers, which might be appealing for modern fabrication techniques. A portable, fully automated device was constructed.
Passive interferometric interrogation of a magnetic field sensor using an erbium doped fiber optic laser with magnetostrictive transducer
2015
Abstract An erbium doped (Er3+) fiber optic laser is proposed for magnetic field measurement. A pair of FBGs glued onto a magnetostrictive material (Terfenol-D rod) modulates the laser wavelength operation when subject to a static or a time dependent magnetic field. A passive interferometer is employed to measure the laser wavelength changes due to the applied magnetic field. A data acquisition hardware and a LabVIEW software measure three phase-shifted signals at the output coupler of the interferometer and process them using two distinct demodulation algorithms. Results show that sensitivity to varying magnetic fields can be tuned by introducing a biasing magnetic field. A maximum error o…
Improved noncontact optical sensor for detection of glucose concentration and indication of dehydration level.
2014
The ability to extract different bio-medical parameters from one single wristwatch device can be very applicable. The wearable device that is presented in this paper is based on two optical approaches. The first is the extraction and separation of remote vibration sources and the second is the rotation of linearly polarized light by certain materials exposed to magnetic fields. The technique is based on tracking of temporal changes of reflected secondary speckles produced in the wrist when being illuminated by a laser beam. Change in skin’s temporal vibration profile together with change in the magnetic medium that is generated by time varied glucose concentration caused these temporal chan…
Laser frequency stabilization by magnetically assisted rotation spectroscopy
2011
Abstract We present a method of Doppler-free laser frequency stabilization based on magnetically assisted rotation spectroscopy (MARS) which combines the Doppler-free velocity-selective optical pumping (VSOP) and magnetic rotation spectroscopy. The stabilization is demonstrated for the atomic rubidium transitions at 780 nm. The proposed method is largely independent of stray magnetic fields and does not require any modulation of the laser frequency. Moreover, the discussed method allows one to choose between locking the laser exactly to the line center, or with a magnetically-controlled shift to an arbitrary frequency detuned by up to several natural linewidths. This feature is useful in ma…
Development of Magnetic Field-Assisted Single-Point Incremental Forming
2021
Single Point Incremental Forming (SPIF) has recently introduced the concept of material formability enhancement through localized deformation. Since material is processed by means of a pin tool attached to spindle, physical interference (especially in vertical direction) limits attainable shapes with the conventional process. The aim of the following work is to increase the variety of achievable geometries with SPIF through in-process magnetic field assistance. An innovative configuration managing SPIF tool movement using magnetic force is proposed. With this in mind, a magnet configuration was designed to generate a vertical load able to plastically deform a 0.5 mm thick AA1100 aluminum sh…