The frequency dependence of magnetization process and giant magneto impedance （GMI） effect of Co-rich melt-extracted amorphous wires was studied by Kerr effect and impedance analyzer, respectively. It is demonstrate...The frequency dependence of magnetization process and giant magneto impedance （GMI） effect of Co-rich melt-extracted amorphous wires was studied by Kerr effect and impedance analyzer, respectively. It is demonstrated that the transverse Kerr intensity and the corresponding GMI response increase with increasing frequency, which contributes to the upgraded skin effect. However, the skin depth has a slothful trend with frequency when it is up to the megahertz range, which gives rise to the transformation of magnetization. The process is much more sensitive to the direct current magnetic field and the sensitive change of the circular permeability, and GMI response is observed as its consequence. This proves that the evolution of circumferential magnetization and the corresponding permeability with the direct current magnetic field is the essence of GMI response, and a much more sensitive magnetization promises a better GMI response.展开更多
Sensitive magnetic field sensor with good performances can be fabricated utilizing the giant magneto-impedance (GMI) effect of soft magnetic multi-layer thin films. The transverse and longitudinal GMI effect in patter...Sensitive magnetic field sensor with good performances can be fabricated utilizing the giant magneto-impedance (GMI) effect of soft magnetic multi-layer thin films. The transverse and longitudinal GMI effect in patterned FeSiB/Cu/FeSiB tri-layer films with the change of external magnetic field and frequency were studied at the same time. The change of the impedance of the films with the external magnetic fieldand frequency was shown. Comparing the longitudinal and transverse effect, the transverse effect has a larger linear range from zero magnetic field to a quite large magnetic field at all frequencies, and the change still were not saturated until the external magnetic field reached 1.2×104A/m, which illustrated that the films can be utilized to detect larger magnetic fields than now presented GMI sensors.展开更多
In order to improve the giant magneto impedance （GMI） of Co-rich wires for high sensitive sensor applications, Co6sFe4.sSilsBlz5 wires were prepared by melt an extraction technique and subjected to Joule stress-curr...In order to improve the giant magneto impedance （GMI） of Co-rich wires for high sensitive sensor applications, Co6sFe4.sSilsBlz5 wires were prepared by melt an extraction technique and subjected to Joule stress-current anneal treatments with different tensile slresses applied. And then their GMI response was investigated at a frequency range from 0.1 to 13 MHz. It was found through the comparison of results that the GMI effect of these wires had been improved through stress-current anneal treatments, because the tensile stress applied on these Co-rich wires introduced magnetoelastic energy and increased anisotropy, which improved the circular permeability and GMI effect. Their impedance ratio AZ/Z increased from 244% to 480.9% at 7 MHz and the field sensitivity increased to 0.83%/（A/m） at 5 MHz, when a tensile stress of 244 MPa was applied at an anneal current of 100 mA for 10 min. It was therefore concluded that these annealed wires were suitable for high sensitive sensor applications.展开更多
SINCE the discovery of the giant magneto-impedance (GMI) effects in amorphous wire (or rib-bon) of CoFeSiB and nanocrystalline wire (or film) of FeCuNbSiB, it has attracted greatattention due to its promising potentia...SINCE the discovery of the giant magneto-impedance (GMI) effects in amorphous wire (or rib-bon) of CoFeSiB and nanocrystalline wire (or film) of FeCuNbSiB, it has attracted greatattention due to its promising potential applications in industry. Amorphous (and nanocrys-talline) soft magnetic alloys have very large magnetic permeability, when an ac driving currentand an external magnetic field (EMF) are applied, the EMF will damp the magnetic fluxchange caused by the ac driving current, thus the magnetic permeability will decrease; as a re-展开更多
IN recent years, giant magneto-resistance (GMR) effects have been observed in some binary composite systems such as multi-layered and granular films of Fe, Co, Ni and Cr, Ag, Cu and attracted considerable interest due...IN recent years, giant magneto-resistance (GMR) effects have been observed in some binary composite systems such as multi-layered and granular films of Fe, Co, Ni and Cr, Ag, Cu and attracted considerable interest due to their potential applications in magnetic recording heads and field sensors. However, a notable GMR effect in these films always requires a strong external magnetic field at low temperature. More recently, Mohri et al. have discovered展开更多
The giant magneto-impedance（GMI）effect of amorphous wire was analyzed theoretically.The amorphous wire had strong GMI effect in the stimulation of sharp pulse of 680kHz and18 mV.A pulse generator was designed to pro...The giant magneto-impedance（GMI）effect of amorphous wire was analyzed theoretically.The amorphous wire had strong GMI effect in the stimulation of sharp pulse of 680kHz and18 mV.A pulse generator was designed to provide high frequency pulse to a magnetic impedance（MI）element.The induced voltage on the pickup coil wound on the amorphous wire was sampled and held with a detect circuit using analog switch.A stable magnetic sensor was constructed.A three-dimension micro magnetic field detector was designed with a central controller MSP430F449.High stability and sensitivity were obtained in the MI sensor with the detect circuit.Experiment results showed that the resolution of the detector was 1nT in the full scale of±2 Oe and the detector worked stably from the room temperature to about 80℃.A small ferromagnetic target was detected by the three-dimension detector in laboratory environment without magnetic shielding.The target moving direction was ascertained with the wave shape of axis parallel in that direction.展开更多
基金financially supported by Taiyuan University of Science and Technology Dr. Start Research Fund (No. 20112002)
文摘The frequency dependence of magnetization process and giant magneto impedance （GMI） effect of Co-rich melt-extracted amorphous wires was studied by Kerr effect and impedance analyzer, respectively. It is demonstrated that the transverse Kerr intensity and the corresponding GMI response increase with increasing frequency, which contributes to the upgraded skin effect. However, the skin depth has a slothful trend with frequency when it is up to the megahertz range, which gives rise to the transformation of magnetization. The process is much more sensitive to the direct current magnetic field and the sensitive change of the circular permeability, and GMI response is observed as its consequence. This proves that the evolution of circumferential magnetization and the corresponding permeability with the direct current magnetic field is the essence of GMI response, and a much more sensitive magnetization promises a better GMI response.
基金This work was supported by the Doctoral Training Foundation of the National Education Commission.
文摘Sensitive magnetic field sensor with good performances can be fabricated utilizing the giant magneto-impedance (GMI) effect of soft magnetic multi-layer thin films. The transverse and longitudinal GMI effect in patterned FeSiB/Cu/FeSiB tri-layer films with the change of external magnetic field and frequency were studied at the same time. The change of the impedance of the films with the external magnetic fieldand frequency was shown. Comparing the longitudinal and transverse effect, the transverse effect has a larger linear range from zero magnetic field to a quite large magnetic field at all frequencies, and the change still were not saturated until the external magnetic field reached 1.2×104A/m, which illustrated that the films can be utilized to detect larger magnetic fields than now presented GMI sensors.
文摘In order to improve the giant magneto impedance （GMI） of Co-rich wires for high sensitive sensor applications, Co6sFe4.sSilsBlz5 wires were prepared by melt an extraction technique and subjected to Joule stress-current anneal treatments with different tensile slresses applied. And then their GMI response was investigated at a frequency range from 0.1 to 13 MHz. It was found through the comparison of results that the GMI effect of these wires had been improved through stress-current anneal treatments, because the tensile stress applied on these Co-rich wires introduced magnetoelastic energy and increased anisotropy, which improved the circular permeability and GMI effect. Their impedance ratio AZ/Z increased from 244% to 480.9% at 7 MHz and the field sensitivity increased to 0.83%/（A/m） at 5 MHz, when a tensile stress of 244 MPa was applied at an anneal current of 100 mA for 10 min. It was therefore concluded that these annealed wires were suitable for high sensitive sensor applications.
文摘SINCE the discovery of the giant magneto-impedance (GMI) effects in amorphous wire (or rib-bon) of CoFeSiB and nanocrystalline wire (or film) of FeCuNbSiB, it has attracted greatattention due to its promising potential applications in industry. Amorphous (and nanocrys-talline) soft magnetic alloys have very large magnetic permeability, when an ac driving currentand an external magnetic field (EMF) are applied, the EMF will damp the magnetic fluxchange caused by the ac driving current, thus the magnetic permeability will decrease; as a re-
文摘IN recent years, giant magneto-resistance (GMR) effects have been observed in some binary composite systems such as multi-layered and granular films of Fe, Co, Ni and Cr, Ag, Cu and attracted considerable interest due to their potential applications in magnetic recording heads and field sensors. However, a notable GMR effect in these films always requires a strong external magnetic field at low temperature. More recently, Mohri et al. have discovered
基金Supported by the National Natural Science Foundation of China(60874100)
文摘The giant magneto-impedance（GMI）effect of amorphous wire was analyzed theoretically.The amorphous wire had strong GMI effect in the stimulation of sharp pulse of 680kHz and18 mV.A pulse generator was designed to provide high frequency pulse to a magnetic impedance（MI）element.The induced voltage on the pickup coil wound on the amorphous wire was sampled and held with a detect circuit using analog switch.A stable magnetic sensor was constructed.A three-dimension micro magnetic field detector was designed with a central controller MSP430F449.High stability and sensitivity were obtained in the MI sensor with the detect circuit.Experiment results showed that the resolution of the detector was 1nT in the full scale of±2 Oe and the detector worked stably from the room temperature to about 80℃.A small ferromagnetic target was detected by the three-dimension detector in laboratory environment without magnetic shielding.The target moving direction was ascertained with the wave shape of axis parallel in that direction.
