A team of researchers from the Immanuel Kant Baltic Federal University (IKBFU) together with their colleagues from Russia, Japan, and Australia studied the influence of inhomogeneity of magnetic field during the fabrication of thin-film structures made from nickel-iron and iridium-manganese alloys, on their properties. These systems can be used in various types of magnetic sensors. The article of the IKBFU team was published in the Journal of Magnetism and Magnetic Materials.Physicists from the IKBFU studied how the inhomogeneous magnetic field, applied during fabrication of thin films made from nickel-iron (NiFe) and iridium-manganese (IrMn), influence its properties. The samples of thin films were made by the magnetron sputtering method. In this technology, a target (a piece of a metal that is to be sputtered) is bombarded by inert atoms (e.g. atoms of a noble gas).
Dr Valeria Rodionova, a co-author of the article, Head of the Laboratory for New Magnetic Materials (IKBFU):
We’ve demonstrated that the presence of an inhomogeneous magnetic field during the manufacture process of thin film exchange-coupled structures changes their magnetization reversal mechanism. If homogenous magnetic fields are used in this process, it leads to the classic shift of the hysteresis loop. Changes in the homogeneity of the magnetic field affect both the value of the loop shift and the shape of the loop in the NiFe/IrMn film structure. We demonstrated that a step-wise hysteresis loop can be obtained for the sample that was created in the area with the highest gradient of the magnetic field. The regularities we discovered will help increase the sensitivity of magnetic field detectors.
The work was carried out in collaboration with scientists from Moscow State University, Tohoku University, University of New South Wales, and National University of Science and Technology MISIS.
Fig. 1. Visualization of a magnetic field between permanent magnets at the location of the substrate for the deposition of NiFe/IrMn film thin-film structure. Courtesy of Dr Valery Rodionov.