Low-Resistivity 10 nm Diameter Magnetic Sensors

Maqableh, Mazin M.; Huang, Xiaobo; Sung, Sang Yeob; Reddy, K. Sai Madhukar; Norby, Gregory; Victora, R. H.; Stadler, Bethanie J. H.

doi:10.1021/nl301610z

Cited by 71 publications

(51 citation statements)

References 75 publications

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“…Magnetic nanoparticles have potential biological and biomedical applications, 1−6 applications in high-resolution magnetic imaging, 7−9 as magnetic sensors, 10 and as dense magnetic storage media. 11 At the same time, the low-dimensionality of these structures results in magnetic configurations not present in macroscopic magnets.…”

Section: Abstract: Magnetic Nanotubes Cantilever Magnetometry Magnementioning

confidence: 99%

Cantilever Magnetometry of Individual Ni Nanotubes

et al. 2012

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Recent experimental and theoretical work has focused on ferromagnetic nanotubes due to their potential applications as magnetic sensors or as elements in high-density magnetic memory. The possible presence of magnetic vortex statesstates which produce no stray fields makes these structures particularly promising as storage devices. Here we investigate the behavior of the magnetization states in individual Ni nanotubes by sensitive cantilever magnetometry. Magnetometry measurements are carried out in the three major orientations, revealing the presence of different stable magnetic states. The observed behavior is well-described by a model based on the presence of uniform states at high applied magnetic fields and a circumferential onion state at low applied fields.

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Section: Abstract: Magnetic Nanotubes Cantilever Magnetometry Magnementioning

confidence: 99%

Cantilever Magnetometry of Individual Ni Nanotubes

et al. 2012

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“…[41][42][43][44] Further design of parameters for potential pulse electrodeposition of CoFe nanowires in quiescent plating solutions were chosen on the basis of the CV experiment shown in Fig. 3a.…”

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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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“…Recent experimental and theoretical work has demonstrated that nanometer-scale magnets, as a result of their low dimensionality, display magnetic configurations not present in their macroscopic counterparts [1][2][3]. Such work is driven by both fundamental questions about nanometerscale magnetism and the potential for applying nanomagnets as elements in high-density memories [4], in high-resolution imaging [5][6][7], or as magnetic sensors [8]. Compared to nanowires, ferromagnetic nanotubes are particularly interesting for magnetization reversal as they avoid the Bloch point structure [9].…”

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Reversal Mechanism of an Individual Ni Nanotube Simultaneously Studied by Torque and SQUID Magnetometry

et al. 2013

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Using an optimally coupled nanometer-scale SQUID, we measure the magnetic flux originating from an individual ferromagnetic Ni nanotube attached to a Si cantilever. At the same time, we detect the nanotube's volume magnetization using torque magnetometry. We observe both the predicted reversible and irreversible reversal processes. A detailed comparison with micromagnetic simulations suggests that vortexlike states are formed in different segments of the individual nanotube. Such stray-field free states are interesting for memory applications and noninvasive sensing.

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Low-Resistivity 10 nm Diameter Magnetic Sensors

Cited by 71 publications

References 75 publications

Cantilever Magnetometry of Individual Ni Nanotubes

Cantilever Magnetometry of Individual Ni Nanotubes

Controlled Electrodeposition and Magnetic Properties of Co₃₅Fe₆₅Nanowires with High Saturation Magnetization

Reversal Mechanism of an Individual Ni Nanotube Simultaneously Studied by Torque and SQUID Magnetometry

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Low-Resistivity 10 nm Diameter Magnetic Sensors

Cited by 71 publications

References 75 publications

Cantilever Magnetometry of Individual Ni Nanotubes

Cantilever Magnetometry of Individual Ni Nanotubes

Controlled Electrodeposition and Magnetic Properties of Co35Fe65Nanowires with High Saturation Magnetization

Reversal Mechanism of an Individual Ni Nanotube Simultaneously Studied by Torque and SQUID Magnetometry

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Controlled Electrodeposition and Magnetic Properties of Co₃₅Fe₆₅Nanowires with High Saturation Magnetization