Nanoscale multifunctional sensor formed by a Ni nanotube and a scanning Nb nanoSQUID

Nagel, J.; Buchter, A.; Xue, Fei; Kieler, Oliver; Weimann, Thomas; Kohlmann, J.; Zorin, A. B.; Rüffer, Daniel; Russo-Averchi, Eleonora; Huber, Rupert; Berberich, P.; Morral, Anna Fontcuberta i; Grundler, D.; Kleiner, R.; Koelle, D.; Poggio, Martino; Kemmler, M.

doi:10.1103/physrevb.88.064425

Cited by 29 publications

(34 citation statements)

References 57 publications

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“…This finding contradicts the assumption of Ref. [19]; we attribute this discrepancy to the fact that while cantilever magnetometry measures the entire volume magnetization, the nanoSQUID is most sensitive to the magnetization at the bottom end of the nanotube, as shown in calculations of the coupling factor ¼ È= (flux È coupled to nanoSQUID by a pointlike particle with magnetic moment ) [20]. Still, we find a one-to-one correspondence between switching fields H sw;e detected by either the nanoSQUID or cantilever magnetometry.…”

Section: Prl 111 067202 (2013) P H Y S I C a L R E V I E W L E T T Econtrasting

confidence: 61%

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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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Section: Prl 111 067202 (2013) P H Y S I C a L R E V I E W L E T T Econtrasting

confidence: 61%

“…Using a scanning nanoSQUID and a cantilever-based torque magnetometer ( Fig. 1) [20], we investigate a Ni nanotube producing ÈðHÞ with a nearly square hysteresis, similar to the Ni nanowire of Ref. [19].…”

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confidence: 99%

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

et al. 2013

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“…Their large saturation magnetization favors fast spin dynamics 25 and provides one with large stray fields from nanoscopic tips, respectively, helping to improve magnetic microscopy. 26 Magnetic nanotubes were fabricated from either Ni or CoFeB by depositing the ferromagnetic shells around bottom-up grown GaAs nanowires. 27,28 The nanowires, which were grown using Ga droplets as catalysts, had lengths between about 10 and 20 μm.…”

Section: -3mentioning

confidence: 99%

Anisotropic magnetoresistance of individual CoFeB and Ni nanotubes with values of up to 1.4% at room temperature

et al. 2014

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Magnetic nanotubes (NTs) are interesting for magnetic memory and magnonic applications. We report magnetotransport experiments on individual 10 to 20 μm long Ni and CoFeB NTs with outer diameters ranging from 160 to 390 nm and film thicknesses of 20 to 40 nm. The anisotropic magnetoresistance (AMR) effect studied from 2 K to room temperature (RT) amounted to 1.4% and 0.1% for Ni and CoFeB NTs, respectively, at RT. We evaluated magnetometric demagnetization factors of about 0.7 for Ni and CoFeB NTs having considerably different saturation magnetization. The relatively large AMR value of the Ni nanotubes is promising for RT spintronic applications. The large saturation magnetization of CoFeB is useful in different fields such as magnonics and scanning probe microscopy using nanotubes as magnetic tips.

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“…Exploiting the duality of our hybrid magnetometer, we measure both the stray magnetic flux generated by the NT with the nanoSQUID and the integrated magnetization by DCM. For the nanoSQUID measurements, the NT-tipped cantilever is positioned for optimal coupling at height z = 1.1 μm above the nanoSQUID's top electrode [9,19]. Despite this proximity of the nanoSQUID to the NT, the magnetic fields produced by the bias and modulation currents running through the nanoSQUID and its superconducting leads are much less than 1 mT at the position of the NT tip and do not significantly influence its magnetization state.…”

Section: Training Effectmentioning

confidence: 99%

Magnetization reversal of an individual exchange-biased permalloy nanotube

et al. 2015

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We investigate the magnetization reversal mechanism in an individual permalloy (Py) nanotube (NT) using a hybrid magnetometer consisting of a nanometer-scale SQUID (nanoSQUID) and a cantilever torque sensor. The Py NT is affixed to the tip of a Si cantilever and positioned in order to optimally couple its stray flux into a Nb nanoSQUID. We are thus able to measure both the NT's volume magnetization by dynamic cantilever magnetometry and its stray flux using the nanoSQUID. We observe a training effect and a temperature dependence in the magnetic hysteresis, suggesting an exchange bias. We find a low blocking temperature T B = 18 ± 2 K, indicating the presence of a thin antiferromagnetic native oxide, as confirmed by x-ray absorption spectroscopy on similar samples. Furthermore, we measure changes in the shape of the magnetic hysteresis as a function of temperature and increased training. These observations show that the presence of a thin exchange-coupled native oxide modifies the magnetization reversal process at low temperatures. Complementary information obtained via cantilever and nanoSQUID magnetometry allows us to conclude that, in the absence of exchange coupling, this reversal process is nucleated at the NT's ends and propagates along its length as predicted by theory.

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Nanoscale multifunctional sensor formed by a Ni nanotube and a scanning Nb nanoSQUID

Cited by 29 publications

References 57 publications

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

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

Anisotropic magnetoresistance of individual CoFeB and Ni nanotubes with values of up to 1.4% at room temperature

Magnetization reversal of an individual exchange-biased permalloy nanotube

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