Effect of boron concentration on the magnetic properties of (FeCoNi) 100−xBx (x=15 and 20 wt%) nanowire arrays

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Abstract

The Fe14.5Co16.5Ni55B15 and the Fe13Co15.5Ni51.5B20 ferromagnetic nanowires were deposited using the electrochemical deposition method. The structure of these nanowires was investigated using X-ray diffraction. Squid magnetometer was used to investigate the magnetic behavior. The hysteresis loops of 50 μm long nanowire arrays were studied as a function of boron concentration, nanowire diameter and field orientation. The competition between shape anisotropy and magnetostatic interactions played a vital role in determining the magnetic field necessary to saturate an array. The decrease in coercive field (Hc) and the squareness (SQ) of the hysteresis loop from 100 to 200 nm wire diameter for both types of compositions suggests the formation of multidomains in the nanowire.

Introduction

Various materials can be produced in an amorphous form by techniques such as vapor deposition, quenching from the melt, ribbons and electrodeposition. The resulting amorphous material not always has the same properties. The material could be very soft, have high electrical resistivity or have exceptionally high corrosion resistance [1]. In order to broaden our understanding about the applications of the material we need to know the behavior of the material. This allows us to tailor the material property so as to suit the needs of a particular device application.

On the other hand, the technological interests like magnetic recording media and the miniaturization of sensors lead to the development of fabrication techniques like nanolithography, molecular beam epitaxy and electrochemical deposition for nanomaterials [2]. Studies on arrays of ferromagnetic nanowires especially on Co, Ni, NiFe, CoNiFe, CoFeB alloys [3], [4], [5], [6] have been carried out in order to understand their physical properties and to assess their usefulness in technical applications. Thus, miniaturization is found to affect the properties of the material.

There is a need to study the magnetostatic interactions amongst the nanowires and the shape anisotropy contribution to understand the magnetic hysteresis loops (MHLs). This paper involves the study of electrodeposited amorphous nanowires. The investigation is based on the role played by the changing boron concentration on the structure and magnetic behavior in the high nickel content (FeCoNi)100−xBx nanowire arrays for x=15 and 20 wt%. The results obtained from the hysteresis loops have been compared to the values given by model in Refs. [2], [3].

Section snippets

Experimental details

FeCoNiB alloy of thickness 50 μm was deposited in the commercially available hexagonal alumina templates (diameters=20, 100 and 200 nm) using the electrochemical deposition method. The electrolyte consisted of iron chloride, cobalt chloride, nickel sulfate and dimethyleaminoborane as sources of Fe, Co, Ni and B, respectively. The boron concentration was changed from 15% to 20% by weight in the FeCoNiB alloy. Boric acid was used as a buffer agent. Work presented here is on Fe14.5Co15.5Ni55B15 and

Morphology and structure of electrodeposited alloys in alumina membranes

The X-ray diffractogram with 10% boron showing partially amorphous phase has been presented in our previous work [7]. The amorphous structure can be seen in Fig. 1, Fig. 2. The X-ray diffraction (XRD) pattern of “electrodeposited” FeCoNiB alloy with varying nanopore diameters is shown for 15% and 20% boron concentrations. Figs. 1(a) and 2(a) show the diffractogram of an alumina template without any alloy deposition, which is compared with the templates with alloy deposition. The main focus is

Conclusions

We have studied the effect of boron concentration on the coercivity, saturation field and squareness of Fe14.5Co15.5Ni55B15 and Fe13Co15.5Ni51.5B20 alloys deposited in templates with varying diameters. The saturation field values obtained from the results in Fig. 3, Fig. 4 agree with few of the saturation field values obtained by the models described in Refs. [2], [3]. This leads us to conclude that although magnetostatic interactions and shape anisotropy play a dominant role in characterizing

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