Tracking walls movement in magnetic wires. Can the shape of the walls be accurately revealed experimentally?

Abstract

Soft amorphous magnetic wires are promising magnetic materials for applications as magnetic logic devices, random access memory, integrated circuits, hard disks, and spintronic devices. These applications are based on the very fast propagation of a single domain wall inside the magnetic wires. Determination of the domain wall structure is an important task due to the role that it plays in the functioning of different applications. In this paper, we analyze the use of the induced signal in a Sixtus–Tonks type experiment to obtain information about domain wall geometry. Although this is a method often used in the scientific literature, we show that without considering the parameters of the detection coil the obtained results can be affected by significant errors. The physical origins of the induced signal are analyzed in this paper, calculating the signal by means of the effective surface and volume magnetization currents, for different types of domain walls. We show that the induced signal is due in part to the domain wall, and in part to the two uniformly magnetized domains separated by the domain wall. The latter contribution exists whatever the shape of the wall, and it can even almost cover the wall contribution. The results are important for understanding and controlling magnetic switching in magnetic wires for future applications. The systematic fundamental theoretical and modeling study presented in this paper is showing the capability and the limits of the inductometric wall detection tools to understand the observed signals measured in experimental setups used in various applications.