Thermally activated magnetization reversal process of self-assembled Fe55Co45 nanowire arrays

Gao, Jian-Hua; Zhan, Qingfeng; He, Wei; Sun, Dali; Cheng, Zhao‐Hua

doi:10.1016/j.jmmm.2006.01.028

Cited by 24 publications

(12 citation statements)

References 36 publications

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“…13 Therefore, controlled deposition to obtain magnetic nanostructures with a high saturation magnetization could be promising for new T2 MRI contrast agents. 14 In the last decade, methods of electrodeposition, as well as the structural and magnetic properties of CoFe nanowire arrays have been extensively investigatied, [15][16][17][18][19][20][21][22][23][24][25][26][27] since CoFe materials have high saturation magnetization, low coercivity and high magnetic shape anisotropy. In order to produce pure CoFe alloy with targeted composition and very high saturation magnetization (B s ≥ 2.4 T), one has to overcome two major challenges.…”

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confidence: 99%

Controlled Electrodeposition and Magnetic Properties of Co₃₅Fe₆₅Nanowires with High Saturation Magnetization

Ghemes

Dragos-Pinzaru

Chiriac

et al. 2016

J. Electrochem. Soc.

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Among all transition metals magnetic alloys, Co 35 Fe 65 possesses the highest saturation magnetization B S = 2.45 T at room temperature given by the so-called "Slater-Pauling limit". For controlled electrodeposition of Co 35 Fe 65 nanowire arrays the following parameters were found to be optimal: electrolyte solution with 1-2 mM malonic acid (MA), ionic ratio Fe +2 /Co +2 = 2.0, growth rate, and pulsed potential deposition with time-on (2.5 s) at the potential of −1.15 V/SCE and time-off (1.0 s) at −0.70 V/SCE. These arrays were deposited inside anodic aluminum oxide (AAO) templates that contained columnar nanopores with diameters either 35 or 200 nm. Cyclic voltammetry was used in solution with and without MA and reaction mechanism was proposed to explain the critical role of MA in electrodeposition of CoFe alloys. In addition to uniform deposition of stechiometric Co 35 Fe 65 alloys, a selectivity ratio, (SR) ∼1.0, were achieved, which means that the atomic ratio of Fe/Co in the nanowire matched the molar ratio of Fe +2 /Co +2 in the electrolyte. The magnetic behavior of the subsequent 2.45 T Co 35 Fe 65 nanowire arrays showed that the shape and magnetostatic anisotropies dominated the effective anisotropy, and the impact of magnetocrystalline and magnetelastic anisotropies field was very small. 1 The highest saturation magnetization of all transition-metal (TM) alloys at room temperature shows Co 36 Fe 65 alloy with respective saturation magnetization of B s = 2.45 T, which is commonly referred to us as the "Slater-Pauling limit".2 Thin films of these alloys, obtained either by electrochemical deposition (ED) or called sputter deposition, are currently used in high areal recording density (HRD) heads including longitudinal (LMR), perpendicular (PMR), and heat assisted (HAMR) magnetic recording. In fact, about 15 years ago Seagate Technologies was first in the recording head industry to introduce 2.4 T CoFe as the longitudinal writer pole material-which was fabricated by electrodeposition. 3 The advantages of electrochemical vs. sputtering deposition include reduced process content, reduced variance and reduced cost. Importantly, controlled electrodeposition is possible even into high aspect ratio of templates including anodized aluminum oxide-AAO, diblock copolymers-DBC, carbonate membranes, and porous silicone. Porous AAO templates are particularly attractive since the pore diameters can be 10-300 nm with pore densities in the range of 10 9 to 10 11 cm −2 . 4 Ferromagnetic nanowire arrays have been used as a miniaturized devices in electronics and optics. 5 In addition, such nanowires have a promising biomagnetic applications like biosensing, cell separation, MRI contrast agents and magnetic hyperthermia. [6][7][8][9][10] Most biomagnetic studies have been limited to nanometer iron-oxide based nanoparticles for MRI imaging and magnetic hyperthermia.6 However, the low saturation magnetization of the bulk iron-oxides (e.g. B s ∼0.5 T for Fe 2 O 3 11 ) prevents them from becoming highly efficient in hypertherm...

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mentioning

confidence: 99%

Controlled Electrodeposition and Magnetic Properties of Co₃₅Fe₆₅Nanowires with High Saturation Magnetization

Ghemes

Dragos-Pinzaru

Chiriac

et al. 2016

J. Electrochem. Soc.

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“…MI change increases with increasing driving current frequency and reaches to a maximum value of 1.45% at 79 MHz. It has been shown that for a typical nanowire, the shape anisotropy could be of the order of 4×10 6 erg/cm 3 [9], which is comparable with other types of anisotropy. Therefore, the maximum change in the MI eect in a nanowire is smaller than that for amorphous alloys or NiFe composite wires.…”

Section: Resultsmentioning

confidence: 72%

Magnetoimpedance Effects in Electrodeposited NiFe Nanowire Array

et al. 2014

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In this work, NiFe nanowires were grown in highly ordered porous anodic alumina oxide templates by dc electrodeposition at a pH value of 2.6. Scanning electron microscopy showed that wires have diameters of about 250 310 nm and length 2530 µm. The energy dispersive X-ray analysis showed that the composition of the nanowires is Ni65Fe35. Electrical contacts were made on both sides of the nanowire array and their magnetoimpedance properties were investigated. All the magnetoimpedance curves showed single peak behavior due to the high shape anisotropy. The maximum magnetoimpedance change at the 79 MHz driving current frequency was ≈ 1.45%.

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“…It has also been reported [35,36] that because of the strong shape anisotropy, nanowire arrays exhibit uniaxial magnetic anisotropy with respect to the easy magnetization direction along the nanowire axes. So, a very different magnetization of nanowires along in-plane in comparison with that along out-of-plane in the present work probably is due to the predominant shape anisotropy contribution.…”

Section: Resultsmentioning

confidence: 89%

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

Najafi

2016

J Supercond Nov Magn

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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.

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Thermally activated magnetization reversal process of self-assembled Fe55Co45 nanowire arrays

Cited by 24 publications

References 36 publications

Controlled Electrodeposition and Magnetic Properties of Co₃₅Fe₆₅Nanowires with High Saturation Magnetization

Controlled Electrodeposition and Magnetic Properties of Co₃₅Fe₆₅Nanowires with High Saturation Magnetization

Magnetoimpedance Effects in Electrodeposited NiFe Nanowire Array

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

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Thermally activated magnetization reversal process of self-assembled Fe55Co45 nanowire arrays

Cited by 24 publications

References 36 publications

Controlled Electrodeposition and Magnetic Properties of Co35Fe65Nanowires with High Saturation Magnetization

Controlled Electrodeposition and Magnetic Properties of Co35Fe65Nanowires with High Saturation Magnetization

Magnetoimpedance Effects in Electrodeposited NiFe Nanowire Array

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

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Controlled Electrodeposition and Magnetic Properties of Co₃₅Fe₆₅Nanowires with High Saturation Magnetization

Controlled Electrodeposition and Magnetic Properties of Co₃₅Fe₆₅Nanowires with High Saturation Magnetization