High frequency magneto impedance in amorphous microwires

Abstract

High frequency magneto impedance in amorphous microwiresToAbstract. We report the novel results on studies of the magneto impedance (MI) effect at GHz-range in 20 µm amorphous glass-coated microwire and 40 µm melt-extracted wire with nearly-zero magnetostriction constant. Both types of wires demonstrated similar behavior although the MI effect is higher in glass-coated microwire. In high field region, when the sample is magnetically saturated, the MI dependence demonstrates typical ferromagnetic resonance behavior. In the low field region the magnetization rotation process is dominant resulting in the highest sensitivity of the impedance to magnetic field. The drawback found in the studied samples is the low field magnetic hysteresis which is undesieble for potential application. The cause of this hysteresis is found to be the helical surface anisotropy in the wires which is characterized by a nonzero angle between the anisotropy easy axis and the wire's transversal plane.

Bimagnetic Microwires, Magnetic Properties, and High-Frequency Behavior

“…The microwave properties of amorphous magnetic alloys have been reported by several groups [12,[46][47][48][49][50][51][52][53]. The main features of FMR in amorphous microwires have been analyzed in several reports [54,55]. The interpretation of rather complex experimental data for multilayer wires with and without intermediate glassy layer has been, however, sometimes contradictory.…”

Microwave behavior in CoFe‐based single‐ and two‐phase magnetic microwires

“…Three samples are considered with the same metallic diameter (17 µm), but different Pyrex thickness so that the total diameter is D = 20, 34, and 42 µm. In order to produce the biphase microwires, a nanometric Au layer was sputtered onto the Pyrex coating and, subsequently a magnetically softer Permalloy (Fe 20 Ni 80 ) or harder Co 90 Ni 10 outer shell with thickness t FeNi · CoNi = 2 µm were galvanostatically grown ( j = 12 mA/cm 2 ) onto the Au layer in typical Watts‐type solutions 6, 8.…”

“…The main features of FMR in amorphous microwires have been analyzed in several reports 5, 6. In the case of biphase microwires, the appearance of multipeak absorption spectra has been recently reported 4, 7; but the origin of the FMR spectra is not clear since the experiments were done for nonfully saturated samples.…”

Fe-Rich Ferromagnetic Wires for Mechanical-Stress Self-Sensing Materials

“…As a matter of fact, while the wire impedance can be easily measured at the low-frequency limit with an oscilloscope by means of the two/four probe method [22], as frequency increases, the probe effect becomes dramatic and the wires tend to radiate. Therefore, high-frequency MI measurements are based on the integration of ferromagnetic wires in transmission lines such as microstrip lines [14]- [16], coaxial cables [23], [24], and waveguides [19]. It is worth remarking that these experiments measure the impedance of the transmission line formed by the wire, and an additional retrieval technique is required to recover the actual wire impedance .…”