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Full-Text Articles in Physics
Polarization Topology At The Nominally Charged Domain Walls In Uniaxial Ferroelectrics, Yurii Tikhonov, Jesi R. Maguire, Conor J. Mccluskey, James P. V. Mcconville, Amit Kumar, Haidong Lu, Dennis Meier, Anna Razumnaya, John Martin Gregg, Alexei Gruverman, Valerii M. Vinokur, Igor Luk’Yanchuk
Polarization Topology At The Nominally Charged Domain Walls In Uniaxial Ferroelectrics, Yurii Tikhonov, Jesi R. Maguire, Conor J. Mccluskey, James P. V. Mcconville, Amit Kumar, Haidong Lu, Dennis Meier, Anna Razumnaya, John Martin Gregg, Alexei Gruverman, Valerii M. Vinokur, Igor Luk’Yanchuk
Department of Physics and Astronomy: Faculty Publications
Ferroelectric domain walls provide a fertile environment for novel materials physics. If a polarization discontinuity arises, it can drive a redistribution of electronic carriers and changes in band structure, which often result in emergent 2D conductivity. If such a discontinuity is not tolerated, then its amelioration usually involves the formation of complex topological patterns, such as flux-closure domains, dipolar vortices, skyrmions, merons, or Hopfions. The degrees of freedom required for the development of such patterns, in which dipolar rotation is a hallmark, are readily found in multiaxial ferroelectrics. In uniaxial ferroelectrics, where only two opposite polar orientations are possible, it …
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 …
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.
Field Induced Domain Wall Collisions In Thin Magnetic Nanowires, Andrew Kunz
Field Induced Domain Wall Collisions In Thin Magnetic Nanowires, Andrew Kunz
Physics Faculty Research and Publications
In a two-dimensional magnetic nanowire, it is possible to engineer collisions between two domain walls put into motion by an externally applied field. We show that the topological defects that define the domain wall can be controlled to allow for both domain wall annihilation and preservation during the collisions as long as the wire remains thin. The preservation process can be used to release pinned domain walls from notches with small applied fields.
Fast Domain Wall Motion In Nanostripes With Out-Of-Plane Fields, Andrew Kunz, Sarah C. Reiff
Fast Domain Wall Motion In Nanostripes With Out-Of-Plane Fields, Andrew Kunz, Sarah C. Reiff
Physics Faculty Research and Publications
Controlling domain wall motion is important due to the impact on the viability of proposed nanowire devices. One hurdle is slow domain wall speed when driven by fields greater than the Walker field due to nucleation of vortices in the wall. We present simulation results detailing the dynamics of these vortices including the nucleation and subsequent fast ejection of the vortex core leading to fast domain wall speeds. The ejection is due to the reversal of the core moments by an out-of-plane field. The technique can be used to produce domain walls of known orientation, independent of the initial state.
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 …
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 …
Magnetization Reversal Of Elliptical Co/Cu/Co Pseudo-Spin Valve Dots, Ngocnga Dao, Scott L. Whittenburg, Y. Hao, Leszek M. Malkinski, Jian Qing Wang, C. A. Ross
Magnetization Reversal Of Elliptical Co/Cu/Co Pseudo-Spin Valve Dots, Ngocnga Dao, Scott L. Whittenburg, Y. Hao, Leszek M. Malkinski, Jian Qing Wang, C. A. Ross
Chemistry and Biochemistry Faculty Publications
We present our recent simulated results on Cr (5 nm)/ Cu (5 nm)/ Co (5 nm)/ Cu (3 nm)/ Co (2 nm) pseudo-spin valve dots. The simulated results agree qualitatively with the experimental results. Three different sizes of elliptical dots, and were simulated. Our simulations show that in these types of dots magnetization reversal occurs by the formation of domain walls: for and for No domain wall was observed in the reversal of the dots. For such dots, the simulated loops show a small two-step reversal pattern with the thin upper layer partially reversing followed by complete reversal of both …
Rayleigh Hysteresis Shape: Its Relationship To Displacement Distance Of A Single Domain Wall In 50% Ni–Fe, R. C. Woodbury, M. R. Hunt
Rayleigh Hysteresis Shape: Its Relationship To Displacement Distance Of A Single Domain Wall In 50% Ni–Fe, R. C. Woodbury, M. R. Hunt
Faculty Publications
The need to measure the displacement distance of domain walls from equilibrium for very weak alternating fields (H ≪ coercive force) in bulk magnetic material has prompted a study of the possible use of the opening of the Rayleigh hysteresis loop to indicate the amount of wall displacement. This paper contains (1) a review of the theoretical relationship between hysteresis shape and the displacement distance of a domain wall, based upon defect-energy models of Rodbell and Bean, and Baldwin; and (2) an experimental approach which provides a measure of the wall displacements versus hysteresis shape for 50% Ni–Fe tape. Discrepancies …