Field and Current Controlled Domain Wall Propagation in Twisted Glass-Coated Magnetic Microwires

S Corodeanu,A Damian,T.-A Óvári,N Lupu,H Chiriac

doi:10.1038/s41598-019-42352-1

Abstract

The torsion effect on the field and current driven magnetization reversal and the associated domain wall velocity in cylindrical amorphous and nanocrystalline glass-coated microwires is reported. Samples from three representative compositions have been investigated: (1) amorphous Fe77.5Si7.5B15 with positive magnetostriction, λ ≅ 25 × 10−6, (2) amorphous Co68.18Fe4.32Si12.5B15 with nearly zero negative magnetostriction, λ ≅ −1 × 10−7, and (3) nanocrystalline Fe73.5Si13.5B9Cu1Nb3 (FINEMET) with small positive magnetostriction, λ ≅ 2.1 × 10−6, all having the diameter of the metallic nucleus, d, of 20 µm and the glass coating thickness, tg, of 11 µm. The results are explained through a phenomenological interpretation of the effects of applied torque on the anisotropy axes within the microwires with different characteristics. Among all the complex mechanical deformations caused by the application of torque on magnetic microwire samples, the most important are the axial compression – for axial field-driven domain wall motion, and the circumferential tension – for electrical current/circumferential field-driven domain wall motion. The Co68.18Fe4.32Si12.5B15 microwire, annealed at 300 °C for 1 hour and twisted at 168 Rad/m exhibits the optimum characteristics, e.g. the lowest switching current (down to 9 mA~2.9 × 10−3 A/cm2) and the largest domain wall velocity (up to 2300 m/s).

Highlights

Only a very few on the effects of a current passing through the sample on the magnetic properties of Co-based microwires[23,24]
Due to the difficulties in monitoring the nucleation of multiple new domains with reversed magnetization and of the associated propagation of the newly formed 180° domain walls within the classical Sixtus-Tonks setup, we have developed a more complex system based on an enhanced variant of the Sixtus-Tonks method, that allows one to correctly identify the domain walls and to measure their DWV31,32, as well as to determine the axial hysteresis loop by an inductive method, in the case of both magnetic field or electric current driven magnetization reversal
In order to analyse and understand the experimental results, we propose a phenomenological interpretation of the effects generated by the two driving forces that produce the magnetization reversal process: (i) the axially applied magnetic field which leads to the axial field-driven DW propagation, and (ii) the circumferential field created by the applied current, which determines the current-driven DW motion

Summary

Introduction

Only a very few on the effects of a current passing through the sample on the magnetic properties of Co-based microwires[23,24]. We report on the torsion effect on the field and current driven hysteresis loop and the associated DWV in cylindrical amorphous and nanocrystalline glass-coated microwires with large positive magnetostriction (FeSiB), small positive magnetostriction (FeSiBCuNb) and nearly zero negative magnetostriction (CoFeSiB). The results have been explained through a phenomenological interpretation of the effects of applied torque on the anisotropy axes within the microwires with different characteristics

Methods

Results

Discussion

Conclusion