The Physics of Metals and Metallography. Vol. 124, No. 1, Pages 1-7, 2023

J. Alam^a, A. Kh. Kh. Zedan^a, M. G. Nematov^c^,^d, N. A. Yudanov^a, A. S. Kurochka^a, A. V. Nuriev^a, L. V. Panina^a^,^b^, *, and V. G. Kostishin^a

^cInstitute of Theoretical and Applied Electrodynamics, Russian Academy of Sciences, Moscow, 125412 Russia

^dDushanbe branch of National University of Science and Technology MISIS, Dushanbe, 734042 Tajikistan

Abstract—The temperature behavior of high-frequency magnetoimpedance (MI) in amorphous microwires in a glass sheath has been studied in the temperature range up to the Curie temperature T_C. Two alloy samples with compositions of Co_27.4Fe₅B_12.26Si_12.26Ni_43.08 (T_C ≈ 48°C) and Co_64.82Fe_3.9B_10.2Si₁₂Cr₉Mo_0.08 (T_C ≈ 61°C) with different signs of magnetostriction constant λ_s and with different types of magnetic anisotropy were used. For the first alloy sample, λ_s < 0, which leads to circular anisotropy. For the second alloy sample, λ_s > 0, and easy axis anisotropy is formed along the wire axis. A substantial decrease in the impedance is observed at elevated frequencies with an increase in the temperature in microwires with easy axis anisotropy, regardless of the application of a magnetic field, while the change in the impedance in wires with circular anisotropy is more substantial in the presence of an external field. Moreover, the change in the impedance with an increase in the temperature from room temperature to T_C can reach 200–300% in the frequency range of 0.5–0.9 GHz in a magnetic field of about 10 Oe. These results may be of interest for the development of miniature temperature sensors.

Keywords: amorphous magnetic microwires, Curie temperature, magnetic impedance, magnetic anisotropy

High-Frequency Magnetic Impedance in (CoFeNi)BSi and (CoFeCrMo)BSi Amorphous Microwires in a Glass Sheath near the Curie Temperature