Magnetic hysteresis in small-grained Co Pd1− nanowire arrays

Abstract

a b s t r a c tCo-Pd nanowires with small grain size are fabricated by AC electrodeposition into hexagonally ordered alumina pores, 20-35 nm in diameter and about 1 mm long. The effects of the alloy composition, the nanowire diameter and the grain size on the hysteresis properties are considered. X-ray diffraction indicates that the nanowires are single phase, a fcc Co-Pd solid solution; electron microscopy results show that they are polycrystalline, with randomly oriented grains (7-12 nm), smaller than the wire diameter. Nanowire arrays are ferromagnetic, with an easy magnetization axis parallel to the nanowire long axis. Both, the coercive field and the loop squareness monotonously increase with the Co content and with the grain size, but no clear correlation with the wire diameter is found. The Co and Co-rich nanowire arrays exhibit coercive fields and reduced remanence values quite insensitive to temperature in the range 4 K-300 K; on the contrary, in Pd-rich nanowires both magnitudes are smaller and they largely increase during cooling below 100 K. These behaviors are systematized by considering the strong dependences displayed by the magneto-crystalline anisotropy and the saturation magnetostriction on composition and temperature. At low temperatures the effective anisotropy value and the domain-wall width to grain size ratio drastically change, promoting less cooperative and harder nucleation modes.

Effect of composition, electrolyte pH, annealing temperature and electrodeposition waveform on the magnetic properties of Co-Cu nanowire alloys

“…Many arrays of magnetic NWs including Fe [24], Co [25], Ni [26], and their alloys [27][28][29] have been prepared via AAO assisted electrodeposition method. Although, there have been numerous publications about ferromagnetic-nonmagnetic alloy NW arrays such as CoPd [30], CoAg [31], FeAg [31], CoPb [32], and CoPt [33] deposited in AAO template, CoCu NW arrays system has been scarcely reported in the literature. The addition of nonmagnetic elements to magnetic elements is one of the most common and effective ways to tune of structural and magnetic properties of magnetic NWs [11].…”

Anodic Alumina Membranes: From Electrochemical Growth to Use as Template for Fabrication of Nanostructured Electrodes

“…Depending on deposition conditions either NTs and NWs were obtained. These materials were selected because having good magnetic properties [75], high electrocatalytic activity [76], they are also excellent sensors for hydrogen gas [77,78].…”