Influence of Composition, pH, Annealing Temperature, Wave Form, and Frequency on Structure and Magnetic Properties of Binary Co1−x Al x and Ternary (Co0.97Al0.03)1−x Fe x Nanowire Alloys

Abstract

Co 1−x Al x and (Co 0.97 Al 0.03 ) 1−x Fe x nanowire alloys and elemental Co nanowire were prepared in anodic aluminum oxide templates by the electrochemical deposition method. The influence of composition, pH, annealing temperature, wave form, and frequency on structure and magnetic properties of Co/Al/Fe nanowires was studied. The changes in the saturation magnetization, coercivity, remanent squareness, and crystal structure of nanowires with changing of the above parameters were also investigated. The roomtemperature magnetic hysteresis loops show that the coercivity and squareness of the nanowire arrays in parallel to the wire axis change with the changing of the abovementioned parameters, which can be mainly attributed to the strengthening of anisotropy. X-ray diffraction observations demonstrated that the isolated nanowires have a crystalline structure and that their phases change with the annealing temperature. Magnetic measurements, on the other hand, showed that the coercivity reached a maximum value at x = 0.03 in the Co 1−x Al x nanowires. Also, the coercivity of the Co 1−x Al x nanowires was increased with increasing annealing temperature for all the compositions.

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

“…The metallic magnetic NWs show very square shape hysteresis loops, which makes these NWs as a very good candidate for magnetic data storage [6][7][8]. It is well known that the addition of nonmagnetic impurities to ferromagnetic NWs can greatly improve their magnetic properties [9][10][11][12]. Among the various methods for the preparation of NWs, including lithography [13], sputtering [14,15], vapor deposition [16], molecular beam epitaxy (MBE) [17], template-assisted electrodeposition is a popular way to obtain a uniform, highly ordered NW arrays and has been shown to be one of the simplest and most inexpensive easily controlled methods [9][10][11][12][18][19][20][21][22][23].…”

“…It is well known that the addition of nonmagnetic impurities to ferromagnetic NWs can greatly improve their magnetic properties [9][10][11][12]. Among the various methods for the preparation of NWs, including lithography [13], sputtering [14,15], vapor deposition [16], molecular beam epitaxy (MBE) [17], template-assisted electrodeposition is a popular way to obtain a uniform, highly ordered NW arrays and has been shown to be one of the simplest and most inexpensive easily controlled methods [9][10][11][12][18][19][20][21][22][23]. On the other hand, the properties of electrodeposited NWs in AAO templates can be controlled by several factors; such as current density, electrolyte composition, time of deposition, temperature, reduction potential (different for each material), pH, microstructure peculiarities etc.…”

“…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]. Although many articles have been published on magnetic and non-magnetic alloys, due to their interesting magnetic and magnetotransport properties, however, no systematic study has been performed on factors.…”