Probe Microscopy in the Investigation of Ni/Cu and FeNi Magnetic Nanowires

Abstract

Тhe work is devoted to studying the magnetic properties of one-dimensional nanostructures: nanowires (NWs). Two types of NWs are obtained by matrix synthesis and studied by probe microscopy. The combination of probe-microscopy modes makes it possible to determine the topography of the nanocrystals and the nature of their magnetization. The change in the magnetization during the application of an external magnetic field (varying in magnitude and direction) is investigated. It is shown that magnetization reversal in an external magnetic field depends on the relative position of the nanowire. Samples of the first type are Ni/Cu layered NWs: their magnetization reversal in an external magnetic field is studied and the magnitude of this field is determined. It is shown that the latter depends on the relative position and interaction of NWs with each other. For a single NW this is 4–5 mT, and for double NWs it is noticeably higher (12–15 mT). An agglomerate consisting of several interacting NWs is undergoes magnetization reversal in stages. The second type of samples are arrays of homogeneous NWs made of FeNi alloy located directly in the growth matrix. The field of magnetization reversal of isolated NWs in all cases is 7–14 mT. On the contrary, in groups of closely located NWs, the switching of magnetization occurs in stages. In this case, the range of switching fields depends on the density of NWs in the matrix and, in general, is much broader than for isolated NWs. In general, it is shown that the magnetic properties of NWs change significantly as the distance between them decreases: their magnetization reversal becomes more difficult, and various intermediate states appear, including those with opposite (antiferromagnetic) magnetization in neighboring NWs.