# An Improved Composition of CoFeSiB Alloy for Orthogonal Fluxgates

^{1}

^{2}

^{3}

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Dependence of the $\mathbf{1}/\mathit{f}$ Noise on the Annealing Time

## 3. Influence of Annealing on the Magnetostriction

## 4. Modified Composition

## 5. Additional Advantage of Long-Time Annealing

## 6. Conclusions

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## References

- Ogasawara, I.; Ueno, S. Preparation and Properties of Amorphous Wires. IEEE Trans. Magn.
**1995**, 31, 1219–1223. [Google Scholar] [CrossRef] - Butta, M.; Janosek, M.; Schutte, B.P.; Vazquez, M.; Perez, R.; Ramirez, E.C.; Jimenez, A. Effect of Amorphous Wire Core Diameter on the Noise of an Orthogonal Fluxgate. IEEE Trans. Magn.
**2018**, 54, 11. [Google Scholar] [CrossRef] - Pokorny, J.; Kraus, L. GMI effect in amorphous wires with creep-induced magnetic anisotropy. Sens. Actuators A Phys.
**1997**, 59, 65–69. [Google Scholar] [CrossRef] - Chen, A.P.; Britel, M.R.; Zhukova, V.; Zhukov, A.; Dominguez, L.; Chizhik, A.B.; Blanco, J.M.; Gonzalez, J. Influence of AC magnetic field amplitude on the surface magnetoimpedance tensor in amorphous wire with helical magnetic anisotropy. IEEE Trans. Magn.
**2004**, 40, 3368–3377. [Google Scholar] [CrossRef] - Aragoneses, P.; Blanco, J.M.; Dominguez, L.; Gonzalez, J.; Kulakowski, K. Influences of the helical anisotropy on the bistable behaviour of amorphous wires. J. Magn. Magn. Mater.
**1997**, 168, 177–181. [Google Scholar] [CrossRef] - Dressler, M.; Janosek, M.; Butta, M. Reduction of magnetic noise limits of orthogonal fluxgate sensor. AIP Adv.
**2021**, 11, 015347. [Google Scholar] [CrossRef] - Tibu, M.; Corodeanu, S.; Hlenschi, C.; Chiriac, H.; Lupu, N. New aspects on the performance of a fundamental mode orthogonal fluxgate magnetometer based on amorphous wire cores. AIP Adv.
**2021**, 11, 015113. [Google Scholar] [CrossRef] - Yuan, Z.; Zhang, Y.; Wang, D.; Jiang, Y.; Guo, R. Research on the Orthogonal Fundamental Mode Fluxgate Sensor Circuit. IEEE Access
**2020**, 8, 150665–150671. [Google Scholar] [CrossRef] - Jiang, H.; Zhang, J.; Xu, Z.; Xu, Y.; Chen, K.; Li, G.; Zeng, P.; Qu, T. Modeling and Performances of the Orthogonal Fluxgate Sensor Operated in Fundamental Mode. IEEE Trans. Magn.
**2020**, 56, 8957362. [Google Scholar] [CrossRef] - Sasada, I. Low-noise fundamental-mode orthogonal fluxgate magnetometer built with an amorphous ribbon core. IEEE Trans. Magn.
**2018**, 54, 8387807. [Google Scholar] [CrossRef] - Chiriac, H.; Tibu, M.; Moga, A.-E.; Herea, D.D. Magnetic GMI sensor for detection of biomolecules. J. Magn. Magn. Mater.
**2005**, 293, 671–676. [Google Scholar] [CrossRef] - Panina, L.V.; Mohri, K. Magneto-impedance effect in amorphous wires. Appl. Phys. Lett.
**1994**, 65, 1189–1191. [Google Scholar] [CrossRef] - Sasada, I. Orthogonal fluxgate mechanism operated with dc biased excitation. J. Appl. Phys.
**2002**, 91, 7789–7791. [Google Scholar] [CrossRef] - Janosek, M.; Butta, M.; Dressler, M.; Saunderson, E.; Novotny, D.; Fourie, C. 1-pT Noise Fluxgate Magnetometer for Geomagnetic Measurements and Unshielded Magnetocardiography. IEEE Trans. Instrum. Meas.
**2020**, 69, 2552–2560. [Google Scholar] [CrossRef] - Koch, R.H.; Rozen, J. Low-noise flux-gate magnetic-field sensors using ring- and rod-core geometries. Appl. Phys. Lett.
**2001**, 78, 1897–1899. [Google Scholar] [CrossRef] - Janosek, M.; Vyhnanek, J.; Zikmund, A.; Butvin, P.; Butvinova, B. Effects of core dimensions and manufacturing procedure on fluxgate noise. Acta Phys. Pol. A
**2014**, 126, 104–105. [Google Scholar] [CrossRef] - Menard, D.; Rudkowska, G.; Clime, L.; Ciureanu, P.; Yelon, A.; Saez, S.; Dolabdjian, C.; Robbes, D.B. Progress towards the optimization of the signal-to-noise ratio in giant magnetoimpedance sensors. Sens. Actuators A Phys.
**2006**, 129, 6–9. [Google Scholar] [CrossRef] - Malatek, M.; Dufay, B.; Saez, S.; Dolabdjian, C.B. Improvement of the off-diagonal magnetoimpedance sensor white noise. Sens. Actuators A Phys.
**2013**, 204, 20–24. [Google Scholar] [CrossRef][Green Version] - Gudoshnikov, S.; Usov, N.; Nozdrin, A.; Ipatov, M.; Zhukov, A.; Zhukova, V. Highly sensitive magnetometer based on the off-diagonal GMI effect in co-rich glass-coated microwire. Phys. Status Solidi Appl. Mater. Sci.
**2014**, 211, 980–985. [Google Scholar] [CrossRef] - Portalier, E.; Dufay, B.; Saez, S.; Dolabdjian, C. Noise behavior of high sensitive GMI-based magnetometer relative to conditioning parameters. IEEE Trans. Magn.
**2015**, 51, 7029202. [Google Scholar] [CrossRef][Green Version] - Traore, P.S.; Asfour, A.; Yonnet, J. Off-diagonal GMI sensors with a software-defined radio detector: Implementation and performance. IEEE Trans. Magn.
**2017**, 53, 7736956. [Google Scholar] [CrossRef] - Traore, P.S.; Asfour, A.; Yonnet, J.; Boudinet, C. Digital electronic conditioning approach for the high-sensitivity off-diagonal GMI sensors. Sens. Actuators A Phys.
**2018**, 271, 290–302. [Google Scholar] [CrossRef] - Bautin, V.A.; Kholodkov, N.S.; Popova, A.V.; Gudoshnikov, S.A.; Usov, N.A. Co-rich amorphous microwires with improved giant magnetoimpedance characteristics due to glass coating etching. JOM
**2019**, 71, 3113–3118. [Google Scholar] [CrossRef] - Butta, M.; Schutte, B.P. Low-Noise Orthogonal Fluxgate Using Flipped Current Joule Annealing. IEEE Trans. Magn.
**2019**, 55, 8638829. [Google Scholar] [CrossRef] - Butta, M.; Yamashita, S.; Sasada, I. Reduction of noise in fundamental mode orthogonal fluxgates by optimization of excitation current. IEEE Trans. Magn.
**2011**, 47, 3748–3751. [Google Scholar] [CrossRef] - Butta, M.; Vazquez, M.; Perez Del Real, R.; Calle, E. Dependence of the noise of an orthogonal fluxgate on the composition of its amorphous wire-core. AIP Adv.
**2020**, 10, 025114. [Google Scholar] [CrossRef] - Butta, M.; Ripka, P.; Janosek, M.; Pribil, M. Electroplated FeNi ring cores for fluxgates with field induced radial anisotropy. J. Appl. Phys.
**2015**, 117, 17A722. [Google Scholar] [CrossRef] - Nielsen, O.V.; Brauer, P.; Primdahl, F.; Risbo, T.; Jorgensen, J.L.; Boe, C.; Deyerler, M.; Bauereisen, S. A high-precision triaxial fluxgate sensor for space applications: Layout and choice of materials. Sens. Actuators A Phys.
**1997**, 59, 168–176. [Google Scholar] [CrossRef] - Benyosef, L.C.; Stael, G.C.; Bochner, M. Optimization of the magnetic properties of materials for fluxgate sensors. Mater. Res.
**2008**, 11, 145–149. [Google Scholar] [CrossRef][Green Version] - Vazquez, M.; Gonzalez, J.; Hernando, A. Induced magnetic anisotropy and change of the magnetostriction by current annealing in Co-based amorphous alloys. J. Magn. Magn. Mater.
**1986**, 53, 323–329. [Google Scholar] [CrossRef] - Yamasaki, J.; Ohkubo, Y.; Humphrey, F.B. Magnetostriction measurement of amorphous wires by means of small angle magnetization rotation. J. Appl. Phys.
**1990**, 67, 5472–5474. [Google Scholar] [CrossRef] - Ripka, P. Magnetic Sensors and Magnetometers; Artech: New York, NY, USA, 2001. [Google Scholar]

**Figure 1.**Dependence of the noise at 1 Hz of an orthogonal fluxgate in fundamental mode based on a single amorphous wire with ${\left({\mathrm{Co}}_{0.94}{\mathrm{Fe}}_{0.06}\right)}_{72.5}{\mathrm{Si}}_{12.5}{\mathrm{B}}_{15}$ composition vs. annealing time.

**Figure 2.**Axial B-H loop of Unitika AC20 wires in its as-cast form and for 1 min and 60 min annealing (

**a**) and the corresponding axial relative permeability (

**b**).

**Figure 3.**Sensitivity of the magnetometer before amplification for an orthogonal fluxgate in fundamental mode based on a single wire vs. annealing time.

**Figure 4.**Saturation magnetostriction constant ${\lambda}_{S}$ of an Unitika wire with ${\left({\mathrm{Co}}_{0.94}{\mathrm{Fe}}_{0.06}\right)}_{72.5}{\mathrm{Si}}_{12.5}{\mathrm{B}}_{15}$ composition vs. annealing time.

**Figure 5.**Saturation magnetostriction constant ${\lambda}_{S}$ (

**a**) and noise (

**b**) at 1 Hz of a wire with a nominal composition of ${\left({\mathrm{Co}}_{0.94}{\mathrm{Fe}}_{0.06}\right)}_{72.5}{\mathrm{Si}}_{12.5}{\mathrm{B}}_{15}$ produced by the National Institute of Research and Development of Technical Physics of Iasi vs. annealing time, together with fitting errors.

**Figure 6.**Saturation magnetostriction constant ${\lambda}_{S}$ (top) of a wire with a nominal composition of ${\left({\mathrm{Co}}_{0.942}{\mathrm{Fe}}_{0.058}\right)}_{72.5}{\mathrm{Si}}_{12.5}{\mathrm{B}}_{15}$, produced at the Institute of Material Sciences of Madrid, vs. annealing time.

**Figure 7.**Noise at 1 Hz of a fluxgate magnetometer based on a wire with a nominal composition of ${\left({\mathrm{Co}}_{0.942}{\mathrm{Fe}}_{0.058}\right)}_{72.5}{\mathrm{Si}}_{12.5}{\mathrm{B}}_{15}$, produced at the Institute of Material Sciences of Madrid vs. annealing time, together with fitting errors.

**Figure 8.**Noise spectra of a fluxgate magnetometer based on a wire with a nominal composition of ${\left({\mathrm{Co}}_{0.942}{\mathrm{Fe}}_{0.058}\right)}_{72.5}{\mathrm{Si}}_{12.5}{\mathrm{B}}_{15}$ produced by the the National Institute of Research and Development of Technical Physics of Iasi, as-cast and after 5 min annealing.

**Figure 9.**Noise spectra of two orthogonal fluxgates based on a single wire with ${\left({\mathrm{Co}}_{0.942}{\mathrm{Fe}}_{0.058}\right)}_{72.5}{\mathrm{Si}}_{12.5}{\mathrm{B}}_{15}$ composition annealed for 10 min and 60 min.

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. |

© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

## Share and Cite

**MDPI and ACS Style**

Butta, M.; Janošek, M.; Pařez, J.; Inchausti, A.V.; Chiriac, H.
An Improved Composition of CoFeSiB Alloy for Orthogonal Fluxgates. *Sensors* **2022**, *22*, 2162.
https://doi.org/10.3390/s22062162

**AMA Style**

Butta M, Janošek M, Pařez J, Inchausti AV, Chiriac H.
An Improved Composition of CoFeSiB Alloy for Orthogonal Fluxgates. *Sensors*. 2022; 22(6):2162.
https://doi.org/10.3390/s22062162

**Chicago/Turabian Style**

Butta, Mattia, Michal Janošek, Jakub Pařez, Alexander Valeriano Inchausti, and Horia Chiriac.
2022. "An Improved Composition of CoFeSiB Alloy for Orthogonal Fluxgates" *Sensors* 22, no. 6: 2162.
https://doi.org/10.3390/s22062162