The GMI profiles of surface-removed amorphous ribbon

Park, D.G.; Moon, E.J.; Rheem, Youngwoo; Kim, C.G.; Hong, Jiang

doi:10.1016/s0921-4526(02)01740-4

Cited by 8 publications

(4 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2,3 As such, the surface roughness of a material is important and can considerably reduce the GMI magnitude if the surface irregularities exceed the skin depth. [4][5][6][7] As an example, reducing the surface irregularities of Co-based amorphous ribbons by chemical polishing was found to greatly enhance the GMI effect. 8 Peksoz et al recently reported that the coating of the Co-based ribbon surface with CuO or a diamagnetic organic thin film improved the GMI effect.…”

mentioning

confidence: 99%

“…On the origin of the enhanced GMI effect in the Cocoated ribbons, we recall that the surface roughness of the sample is important when the skin effect is strong. [2][3][4][5][6] This is not only because the skin depth may become smaller than the surface irregularities, but also because stray fields that arise from rough surfaces cause a considerable reduction in the GMI magnitude. 3,5,6 In the present case, the calculated values of d m [ Fig.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Enhanced giant magnetoimpedance effect and field sensitivity in Co-coated soft ferromagnetic amorphous ribbons

Laurita

Chaturvedi

Bauer

et al. 2011

Journal of Applied Physics

View full text Add to dashboard Cite

A 50 nm-thick Co film has been grown either on the free surface (surface roughness, $6 nm) or on the wheel-side surface (surface roughness, $147 nm) of Co 84.55 Fe 4.45 Zr 7 B 4 amorphous ribbons. A comparative study of the giant magnetoimpedance (GMI) effect and its field sensitivity (g) in the uncoated and Co-coated ribbons is presented. We show that the presence of the Co coating layer enhances both the GMI ratio and g in the Co-coated ribbons. Larger values for GMI ratio and g are achieved in the sample with Co coated on the free ribbon surface. The enhancement of the GMI effect in the Co-coated ribbons originates mainly from the reduction in stray fields due to surface irregularities and the enhanced magnetic flux paths closure. These findings provide good guidance for tailoring GMI in surface-modified soft ferromagnetic ribbons for use in highly sensitive magnetic sensors. The discovery of the so-called giant magnetoimpedance (GMI) effect in soft ferromagnetic ribbons makes them attractive for magnetic sensor applications. 1,2 GMI is a large change in the ac impedance of a ferromagnetic conductor subject to a dc magnetic field. 1 The impedance (Z) of a ferromagnetic ribbon can be calculated by 3 Z ¼ R dc jka cothðjkaÞ;( 1) where a is half of the thickness of the ribbon, R dc is the electrical resistance for a dc current, j ¼ imaginary unit, andThe impedance is related to the skin effect characterized by the skin depth (d m ), which, in a magnetic medium, is given bywhere q is the electrical resistivity, m T is the transverse magnetic permeability, and f is the frequency of the ac current. The application of a dc magnetic field H dc changes m T , and consequently d m and Z. Since GMI is observed at high frequencies (>1 MHz), the skin effect is significant enough to confine the ac current to a sheath close to the surface of the conductor; GMI is therefore a surface-related magnetic phenomenon. 2,3 As such, the surface roughness of a material is important and can considerably reduce the GMI magnitude if the surface irregularities exceed the skin depth. [4][5][6][7] As an example, reducing the surface irregularities of Co-based amorphous ribbons by chemical polishing was found to greatly enhance the GMI effect. 8 Peksoz et al. recently reported that the coating of the Co-based ribbon surface with CuO or a diamagnetic organic thin film improved the GMI effect. 9,10 While the origin of the enhanced GMI effect in the samples 9,10 is not well understood, these investigations open up new opportunities for improving GMI effect in soft ferromagnetic ribbons. We report here a comparative study of the GMI effect and its field sensitivity (g) in Co 84.55 Fe 4.45 Zr 7 B 4 amorphous ribbons with and without 50 nm thick Co layers deposited on either the free ribbon surface (surface roughness, $6 nm) or on the wheel-side ribbon surface (surface roughness, $147 nm). This composition has a high Curie temperature compared to Fe-based amorphous alloys 11 and is responsive to field annealing. 12 We find a large enhancement of th...

show abstract

mentioning

confidence: 99%

mentioning

confidence: 99%

Enhanced giant magnetoimpedance effect and field sensitivity in Co-coated soft ferromagnetic amorphous ribbons

Laurita

Chaturvedi

Bauer

et al. 2011

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…As the annealing time increases, the hysteresis decreases and the on-set fields GMI-valve in the 8 h annealed sample for the increasing and decreasing fields nearly coincide with each other. These GMI-valve characteristics did not appear in the sample without an oxidation layer [3]. Therefore, it can be concluded that the GMI-valve structure has come from the crystalline phase created by the surface oxidation.…”

Section: Resultsmentioning

confidence: 81%

Study of GMI-valve characteristics in the Co-based amorphous ribbon by ferromagnetic resonance

Park

Kim

et al. 2007

Journal of Magnetism and Magnetic Materials

Self Cite

View full text Add to dashboard Cite

“…As microwave power interacts with a smaller part of crystal its losses decrease, leading to a decrease in the absorption when the temperature is lower than 55 K. The dependence of the absorption amplitude on the magnetic field strength could arise from the magnetoimpedance (MI) effect. This effect was studied extensively in Co-based amorphous alloys [36,37]. In terms of the MI effect description, the complex surface impedance Z ≈ √ ωµ/σ , where ω is the frequency and µ and σ are the complex permeability and conductivity, respectively.…”

Section: Discussionmentioning

confidence: 99%

Resonance and non-resonance microwave absorption in cobaltites

Aleshkevych¹,

Баран²,

Barilo³

et al. 2004

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

Microwave studies in the temperature range 4–300 K have been made on the different kinds of cobaltites in an attempt to observe a magnetic resonance. In a La0.9Ca0.1CoO3 single crystal a broad resonance absorption line (with ) due to the presence of Co4+ ions was observed below 40 K. The measured broadening of the linewidth with decreasing temperature can be related to the process of clustering of cobalt ions. In La0.8Ca0.2CoO3 and TbBaCo2O5.5 single crystals non-resonance absorption was observed in the temperature ranges 20–90 and 240–260 K, respectively. In order to investigate the nature of this absorption its intensity was measured as a function of external magnetic field and temperature. The results could suggest that the absorption, although similar for both compounds, was caused by two different mechanisms: microwave power losses on metallic/ferromagnetic clusters in La0.8Ca0.2CoO3 and high-frequency fluctuations of the magnetic domain walls in TbBaCo2O5.5.

show abstract

The GMI profiles of surface-removed amorphous ribbon

Cited by 8 publications

References 10 publications

Enhanced giant magnetoimpedance effect and field sensitivity in Co-coated soft ferromagnetic amorphous ribbons

Enhanced giant magnetoimpedance effect and field sensitivity in Co-coated soft ferromagnetic amorphous ribbons

Study of GMI-valve characteristics in the Co-based amorphous ribbon by ferromagnetic resonance

Resonance and non-resonance microwave absorption in cobaltites

Contact Info

Product

Resources

About