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Full-Text Articles in Physics
Magnetization Reversal In Ferromagnetic Spirals Via Domain Wall Motion, Ryan D. Schumm, Andrew Kunz
Magnetization Reversal In Ferromagnetic Spirals Via Domain Wall Motion, Ryan D. Schumm, Andrew Kunz
Physics Faculty Research and Publications
Domain wall dynamics have been investigated in a variety of ferromagnetic nanostructures for potential applications in logic, sensing, and recording. We present a combination of analytic and simulated results describing the reliable field driven motion of a domain wall through the arms of a ferromagnetic spiral nanowire. The spiral geometry is capable of taking advantage of the benefits of both straight and circular wires. Measurements of the in-plane components of the spirals' magnetization can be used to determine the angular location of the domain wall, impacting the magnetoresistive applications dependent on the domain wall location. The spirals' magnetization components are …
Selection And Control Of Individual Domain Walls In Nanowire Arrays Via Asymmetric Depinning Fields, Andrew Kunz, H. Henry Le, Demetrious Kutzke, Jesse Vogeler-Wunsch
Selection And Control Of Individual Domain Walls In Nanowire Arrays Via Asymmetric Depinning Fields, Andrew Kunz, H. Henry Le, Demetrious Kutzke, Jesse Vogeler-Wunsch
Physics Faculty Research and Publications
Artificially inscribed notches are often used to pin domain walls (DWs) in ferromagnetic nanowires. The process of selecting and moving the trapped DW in nanowire arrays is an important step for potential applications. The chirality of a DW leads to a pair of pinning positions at the inscribed notches, which can be modeled by a symmetric double well. The depinning field depends on the side of the well, the DW is trapped with respect to the applied field direction, and the DWs can also be transitioned between the two wells without depinning. We demonstrate how manipulating the double well improves …
Antivortex Dynamics In Magnetic Nanostripes, Andrew Kunz, Eric C. Breitbach, Andy J. Smith
Antivortex Dynamics In Magnetic Nanostripes, Andrew Kunz, Eric C. Breitbach, Andy J. Smith
Physics Faculty Research and Publications
In a thin magnetic nanostripe, an antivortex nucleates inside a moving domain wall when driven by an in-plane magnetic field greater than the so-called Walker field. The nucleated antivortex must cross the width of the nanostripe before the domain wall can propagate again, leading to low average domain wall speeds. A large out-of-plane magnetic field, applied perpendicularly to the plane of the nanostripe, inhibits the nucleation of the antivortex leading to fast domain wall speeds for all in-plane driving fields. We present micromagnetic simulation results relating the antivortex dynamics to the strength of the out-of-plane field. An asymmetry in the …
Dependence Of Domain Wall Structure For Low Field Injection Into Magnetic Nanowires, Andrew Kunz, Sarah C. Reiff
Dependence Of Domain Wall Structure For Low Field Injection Into Magnetic Nanowires, Andrew Kunz, Sarah C. Reiff
Physics Faculty Research and Publications
Micromagnetic simulation is used to model the injection of a domain wall into a magnetic nanowire with field strengths less than the so-called Walker field. This ensures fast, reliable motion of the wall. When the wire is located at the edge of a small injecting disk, a bias field used to control the orientation of the domain wall can reduce the pinning potential of the structure. The low field injection is explained by a simple model, which relies on the topological nature of a domain wall. The technique can quickly inject multiple domain walls with a known magnetic structure.
Enhancing Domain Wall Speed In Nanowires With Transverse Magnetic Fields, Andrew Kunz, Sarah C. Reiff
Enhancing Domain Wall Speed In Nanowires With Transverse Magnetic Fields, Andrew Kunz, Sarah C. Reiff
Physics Faculty Research and Publications
Dynamic micromagnetic simulation studies have been completed to observe the motion of a domain wall in a magnetic nanowire in an effort to increase the field-driven domain wall speed. Previous studies have shown that the wire dimensions place a cap on the maximum speed attainable by a domain wall when driven by a magnetic field placed along the direction of the nanowire. Here we present data showing a significant increase in the maximum speed of a domain wall due to the addition of a magnetic field placed perpendicular to the longitudinal driving field. The results are expressed in terms of …
Micromagnetics Of The Domain Wall Mobility In Permalloy Nanowires, Andrew Kunz
Micromagnetics Of The Domain Wall Mobility In Permalloy Nanowires, Andrew Kunz
Physics Faculty Research and Publications
The domain wall mobility in long permalloy nanowires with thicknesses of 2-20 nm and widths of 50-200 nm has been simulated. The domain wall is driven into motion by an external magnetic field and the average wall mobility is calculated after the wall has traveled 2.5 mum along the wire. The results were obtained using the three-dimensional dynamic Landau-Lifshitz equation. We find that the domain wall mobility decreases linearly up to the critical field called the Walker field. The decreasing wall mobility is related to the decrease in the dynamic domain wall length as the applied field is increased. The …
Simulated Domain Wall Dynamics In Magnetic Nanowires, Andrew Kunz
Simulated Domain Wall Dynamics In Magnetic Nanowires, Andrew Kunz
Physics Faculty Research and Publications
The simulated domain wall dynamics in rectangular 10 nm thick, 2000 nm long Permalloy wires of varying width is presented. In the absence of an applied field the static domain wall length is found to be linearly dependent to the width of the nanowire. As magnetic fields of increasing strength are applied along the wire’s long axis, the domain wall motion changes from a uniform reversal to a steplike reversal. The onset of the stepping motion leads to a decrease in the domain wall speed. By continuing to increase the field it is possible to decrease the time between steps …