Metastable states in magnetic nanorings

Castaño, Fernando; Ross, Caroline A.; Frandsen, Cathrine; Eilez, A.; Gil, Darı́o; Smith, Henry I.; Redjdal, M.; Humphrey, F. B.

doi:10.1103/physrevb.67.184425

Cited by 194 publications

(162 citation statements)

References 22 publications

Supporting

Mentioning

149

Contrasting

Order By: Relevance

“…In such structures, the DW velocity can be precisely clocked with a rotating field. Prior to experiments, a large in-plane magnetic field was applied to coerce the tracks into an "onion" domain configuration, with two circumferential magnetic domains separated by DWs lying along the field axis 34,[37][38][39][40] . A dilute suspension of SPM beads was then placed in a polydimethylsiloxane (PDMS) well on the wafer surface and sealed with a microscope cover slip.…”

Section: Maximum Velocity Measurementmentioning

confidence: 99%

Transport dynamics of superparamagnetic microbeads trapped by mobile magnetic domain walls

Rapoport

Beach

2013

Phys. Rev. B

View full text Add to dashboard Cite

The dynamics of fluid-borne superparamagnetic bead transport by field-driven domain walls in submicrometer ferromagnetic tracks is studied experimentally together with numerical and analytical modeling. A combination of micromagnetic modeling and numerical calculation is used to determine the strength of bead-domain wall interaction for a range of track geometries and bead sizes. The maximum domain wall velocity for continuous bead transport is predicted from these results and shown to be supported by experimental measurements. Enhancement of the maximum velocity by appropriate material selection or field application is demonstrated and an analysis of the source of statistical variation is presented. Finally, the dynamics of beaddomain wall interaction and bead transport above the maximum domain wall velocity for continuous domain wall-mediated bead transport is characterized.Submitted to Phys. Rev. B 2

show abstract

Section: Maximum Velocity Measurementmentioning

confidence: 99%

Transport dynamics of superparamagnetic microbeads trapped by mobile magnetic domain walls

Rapoport

Beach

2013

Phys. Rev. B

View full text Add to dashboard Cite

show abstract

“…For the elliptical ring, the magnetoresistance data shows a f at baseline and very abrupt transitions as the domain walls in the NiFe layer sweep through the region limited by the voltage contacts. As the reverse f eld increases, the propagating domain walls in the NiFe meet, forming a 360 • wall on each side of the elliptical ring, similar to the 360 • walls reported in small circular rings ('twistedonion' state) [66,98,103]; the 360 • walls have an insignif cant effect on the GMR, and since the Co layer is still in the onion state, the resistance of the ring is maximum. The intermediate resistance level corresponds to the switching of the Co layer to the vortex state and the transition to the reverse onion state results again in a minimum resistance value [99].…”

Section: Magnetic Properties Of Spin-valve Ring Elementsmentioning

confidence: 79%

“…These are representative of two types of magnetic reversal that can occur in small elements: domain wall propagation, and domain nucleation plus wall propagation. In the transition from onion to vortex state one of the 180 • domain walls is displaced and propagates along one half of the ring (annihilating the other domain wall or else forming metastable 360 • domain walls, depending on the relative winding [66]). Which of the walls is displaced and in which direction, and consequently which vortex circulation results, depends on the local pinning potential, and recent experimental results indicate that this process is governed by a stochastic mechanism due to thermal f uctuations [67].…”

Section: Field Induced Magnetic Switchingmentioning

confidence: 99%

Ferromagnetic Nanorings

et al. 2007

View full text Add to dashboard Cite

Ferromagnetic metal rings of nanometre range widths and thicknesses exhibit fundamentally new spin states, switching behaviour and spin dynamics, which can be precisely controlled via geometry, material composition and applied f eld. Following the discovery of the 'onion state', which mediates the switching to and between vortex states, a range of fascinating phenomena has been found in these structures. In this overview of our work on ring elements, we f rst show how the geometric parameters of ring elements determine the exact equilibrium spin conf guration of the domain walls of rings in the onion state, and we show how such behaviour can be understood as the result of the competition between the exchange and magnetostatic energy terms. Electron transport provides an extremely sensitive probe of the presence, spatial location and motion of domain walls, which determine the magnetic state in individual rings, while magneto-optical measurements with high spatial resolution can be used to probe the switching behaviour of ring structures with very high sensitivity. We illustrate how the ring geometry has been used for the study of a wide variety of magnetic phenomena, including the displacement of domain walls by electric currents, magnetoresistance, the strength of the pinning potential introduced by nanometre size constrictions, the effect of thermal excitations on the equilibrium state and the stochastic nature of switching events.

show abstract

“…The initiation of the reversal of M appeared to take place by the generation of domains in some sections of the ring and not by the depinning and movement of the DWs, as was observed in rings with circumferential magnetization that exhibit onion and vortex states. [11][12][13] For H = 16.7 kA/m, the domains parallel to the field were enlarged by movement of domain walls and, at 32 kA/m, the inversion of the polarity of M was nearly complete. The fact that the polarity of the contrast of the ring followed the field direction suggests that the tip magnetization was maintained perpendicular to H and was not demagnetized during the measurements.…”

Section: Resultsmentioning

confidence: 99%

Strain-induced magnetization reorientation in epitaxial Cu/Ni/Cu rings

et al. 2013

Self Cite

View full text Add to dashboard Cite

The role of the strain state in epitaxial (001)-oriented Cu/Ni(14 nm)/Cu rings is investigated using a combination of magnetic force microscopy and finite-element calculations. Rings with an external diameter of 3 and 2 μm and linewidth W larger than 400 nm show two different structures: domains with magnetization oriented in the radial direction exist at the inner and outer radius, separated by an area in the interior of the ring consisting of stripe domains with perpendicular magnetization. The former is the sole magnetic structure observed for W < 400 nm. Micromagnetic calculations on narrow-linewidth structures indicate that the radial domain-wall structure consists of elliptical Bloch lines with a shorter and longer length along the tangential and radial directions, respectively. Finite-element calculations show that the anisotropic relaxation of the in-plane strain is larger at the ring inner and outer edges than in the interior part of the ring and accounts for the reorientation of the magnetization direction.

show abstract

Metastable states in magnetic nanorings

Cited by 194 publications

References 22 publications

Transport dynamics of superparamagnetic microbeads trapped by mobile magnetic domain walls

Transport dynamics of superparamagnetic microbeads trapped by mobile magnetic domain walls

Ferromagnetic Nanorings

Strain-induced magnetization reorientation in epitaxial Cu/Ni/Cu rings

Contact Info

Product

Resources

About