Magneto-resistance, magneto-reactance, and magneto-impedance effects in single and multi-wire systems

physica status solidi (a), 2008

IEEE Transactions on Magnetics, 1998

A magneto-impedance (MI) effect has been experimentally detected and systematically studied in Co 68:5 Mn 6:5 Si 10 B 15 glass-coated amorphous microwire 14 m in diameter. The dependence of MI on a dc applied magnetic field (up to 20 Oe) for a range of values of ac current (less than 4 mA and having a frequency between 0.2 and 2.0 MHz) flowing along the microwire has been measured in as-prepared samples, as well as after heat treatments up to 400 C. A maximum relative change in MI of around 16% is observed in the optimum conditions, that is, for about 5 Oe dc axial applied field and 3 mA, 2 MHz ac current flowing along the microwire, which finally corresponds to a magnetic field sensitivity of about 0.4 V/Oe. Such modifications are interpreted considering the dependence of the skin-effect on those parameters through the induced changes in the circular permeability. MI in these ferromagnetic wires with micrometric dimension is of technological interest for local detection of magnetic fields.

sensors, 2020

Amorphous soft magnetic microwires have attracted much attention in the area of sensor applications due to their excellent properties. In this work, we study the influence of annealing treatments (stress and conventional) in the giant magnetoimpedance (GMI) response and the field sensitivity of the soft magnetic Co 69.2 Fe 3.6 Ni 1 B 12.5 Si 11 Mo 1.5 C 1.2 glass-coated microwires. Here we report a remarkable and simultaneous enhancement of GMI effect and field sensitivity. The highest sensitivity of 104%/Oe and the GMI response of 234% were achieved for 300 • C stress-annealed samples at 472 and 236 MPa, respectively. Additionally, we found that stress-annealed microwires exhibit a frequency dependence on maximal GMI response and field sensitivity. These findings are obtained by fine-tuning their magnetoeslastic anisotropies through stress-annealing treatments of as-prepared microwires at the proper temperature and axial applied stress upon annealing. We hope that the results presented here widen the scope of investigations for the future design of soft magnetic materials for sensor purposes.

physica status solidi (a), 2014

The design and performance of a magnetometer based on the offdiagonal GMI effect in Co-rich glass-coated microwire are presented. The sensing element of the magnetometer is a 10-mm long piece of Co-Fe-Ni-B-Si-Mo microwire with a small pick-up coil of 85 turns wounded around the microwire. The electronics with a feedback circuit is used to register an electromotive force proportional to the external magnetic field applied along the wire axis. In the absence of the feedback current the magnetometer is capable of measuring a narrow range of magnetic fields, AE3.5 mT, in the frequency range of 0-1 kHz, the level of the equivalent magnetic noise being about 10 pT Hz À1/2 at a frequency of 300 Hz. The use of the feedback circuit increases the range of the measured magnetic fields up to AE250 mT.

Applied Physics Letters, 2010

We have investigated the impedance dependence of magnetically soft microwire on the internal circumferential magnetic field H B created by the dc bias current I B and theoretically and experimentally demonstrated that in a conductor with helical magnetic anisotropy, the high frequency impedance depends on the dc bias current I B ͑or the corresponding bias field H B ͒ and this dependence is hysteretic. We have experimentally observed a change of impedance more than 35% upon changing the bias current. The possible applications of the dc current-driven magnetoimpedance effect are discussed.

Journal of Electronic Materials, 2018

Two soft ferromagnetic Co 68.25 Fe 4.25 Si 12.25 B 15.25 microwires with the same diameter of 50 ± 1 lm but different fabrication processes were placed in series and in parallel circuit configurations to investigate their giant magneto-impedance (GMI) responses in a frequency range of 1-100 MHz for low-field sensing applications. We show that, while the low-field GMI response is significantly reduced in the parallel configuration, it is greatly enhanced in the series connection. These results suggest that a highly sensitive GMI sensor can be designed by arranging multi-wires in a saw-shaped fashion to optimize the sensing area, and soldered together in series connection to maintain the excellent magnetic field sensitivity.

IEEE Magnetics Letters, 2016

The magnetic properties of as-prepared and annealed amorphous Co50.69Fe8.13Ni17.55B13.29Si10.34 glasscoated microwires produced by the Taylor-Ulitovsky technique are investigated systematically. Magnetic-field frequency dependencies of magneto-impedance (MI), domain-wall (DW) velocity, and hysteresis loops were measured. At certain annealing conditions, high MI and fast DW propagation coexist. The results suggest criteria for the selection of materials for high-performance magnetic sensors.

International Journal on Smart Sensing and Intelligent Systems, 2020

We studied the Giant magnetoimpedance (GMI) effect and magnetic properties of amorphous Fe-Co rich magnetic microwires prepared by the Taylor-Ulitovski technique. We observed that these properties can be tailored either controlling magnetoelastic anisotropy of as-prepared Co-rich microwires or controlling their magnetic anisotropy by heat treatment. High GMI effect even at GHz frequencies has been observed in Co-rich microwires.

Journal of Non-Crystalline Solids, 2001

The giant magnetoimpedance (GMI) eect has been measured in Co 83:2 B 3:3 Si 5:9 Mn 7:6 amorphous microwire as a function of direct current (dc)-biased current and measuring frequency, f. The GMI pro®le has a single peak for f 6 5 MHz, and two peaks at higher frequency. The maximum GMI ratio increases continuously with frequency up to 45% at 10 MHz. The in¯uence of superimposed dc biasing is shown to result in asymmetrical GMI as well as in a shift of the axial hysteresis loop. Both eects are interpreted in terms of the relative contribution of domain wall and rotational processes to the transverse susceptibility.

Journal of Physics: Conference Series, 2009

Currently, the design and development of novel magnetic materials with optimized properties is of relevance to study new phenomena and to use them for multifunctional applications of sensor technologies and magnetoelectronic devices. In this letter, we present a detailed investigation of giant magnetoimpedance (GMI) effect in layered magnetic microwires. A new family of layered microwire composite materials was fabricated by using rapidly quenching and coating techniques. The experimental measurements were performed using an impedance analyzer (HP 4191A) in the frequency range of 100 -1000 MHz and a varying applied dc magnetic field within 300 Oe. Interestingly, the GMI ratio and magnetic-field sensitivity reached the largest values of 3200 and 2400%/Oe at a resonance frequency of 890.15 MHz for layered Corich microwire sample, respectively. These results are very ideal for the development of a new family of ultra-sensitive and high-frequency magnetic sensors. Finally, the layered composite magnetic micro-wire developed with enhanced sensitivity performance can be ideally used as sensing elements in magnetic sensor technologies.