Equilibrium states and vortex domain wall nucleation in ferromagnetic nanotubes

Landeros, P.; Suarez, O. J.; Cuchillo, A.; Vargas, P.

doi:10.1103/physrevb.79.024404

Cited by 98 publications

(140 citation statements)

References 24 publications

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“…Such configurations avoid the magnetic point singularity along the axis of the structure, 16 thereby resulting in a fast and controllable reversal process. 17 In addition, previously unforeseen dynamic effects are possible in nanotubes. Domain walls moving in nanotubes are predicted to avoid a Walker breakdown and give rise to Cherenkov-like spin wave emission.…”

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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“…The observed magnetization steps suggest the presence of 2 to 4 intermediate magnetic states or 2 to 4 segments in the nanotube that switch at different H. Calculations for ideal nanotubes [10] suggest that the intermediate states should be multidomain, consisting of uniform axially saturated domains separated by azimuthal or vortexlike domain walls. The preferred sites for domain nucleation are expected to be the two ends of the nanotube [9,10].…”

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

confidence: 99%

“…The preferred sites for domain nucleation are expected to be the two ends of the nanotube [9,10]. As the field is reduced after saturation, magnetic moments should gradually curl or tilt away from the field direction.…”

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

confidence: 99%

“…Compared to nanowires, ferromagnetic nanotubes are particularly interesting for magnetization reversal as they avoid the Bloch point structure [9]. Different reversal processes via curling, vortex wall formation, and propagation have been predicted [10][11][12][13]. Because of their inherently small magnetic moment, experimental investigations have often been conducted on large ensembles.…”

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confidence: 99%

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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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“…First, the differences observed in the hysteresis measured by the nanoSQUID and by DCM indicate that magnetization reversal likely nucleates at the ends of the NT and subsequently propagates throughout its length, as predicted by theory [24]. In this picture, vortex configurations form at the NT ends, begin tilting in the direction of the applied field, and subsequently cause magnetization reversal by propagating throughout the length of the tube and discontinuously switching to a uniform configuration aligned along the applied field.…”

Section: Training Effectmentioning

confidence: 95%

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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Equilibrium states and vortex domain wall nucleation in ferromagnetic nanotubes

Cited by 98 publications

References 24 publications

Cantilever Magnetometry of Individual Ni Nanotubes

Cantilever Magnetometry of Individual Ni Nanotubes

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

Magnetization reversal of an individual exchange-biased permalloy nanotube

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