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Articles 1 - 7 of 7
Full-Text Articles in Physics
Electron-Induced Massive Dynamics Of Magnetic Domain Walls, Hilary M. Hurst, Victor Galitski, Tero T. Heikkilä
Electron-Induced Massive Dynamics Of Magnetic Domain Walls, Hilary M. Hurst, Victor Galitski, Tero T. Heikkilä
Faculty Research, Scholarly, and Creative Activity
We study the dynamics of domain walls (DWs) in a metallic, ferromagnetic nanowire. We develop a Keldysh collective coordinate technique to describe the effect of conduction electrons on rigid magnetic structures. The effective Lagrangian and Langevin equations of motion for a DW are derived. The DW dynamics is described by two collective degrees of freedom: position and tilt-angle. The coupled Langevin equations therefore involve two correlated noise sources, leading to a generalized fluctuation-dissipation theorem (FDT). The DW response kernel due to electrons contains two parts: one related to dissipation via FDT, and another `inertial' part. We prove that the latter …
Unpinning The Skyrmion Lattice In Mnsi: Effect Of Substitutional Disorder, Chetan Dhital, L. Debeer-Schmitt, D. P. Young, J. F. Ditusa
Unpinning The Skyrmion Lattice In Mnsi: Effect Of Substitutional Disorder, Chetan Dhital, L. Debeer-Schmitt, D. P. Young, J. F. Ditusa
Faculty and Research Publications
By employing magnetization and small angle neutron scattering measurements, we have investigated the behavior of the skyrmion lattice (SKL) and the helical order in MnS i 0 . 992 G a 0 . 008 Our results indicate that the order of the SKL is sensitive to the orientation of an applied magnetic field with respect to the crystal lattice and to variations in the sequence of small temperature and applied magnetic field changes. The disorder caused by the substitution of the heavier element Ga for Si is sufficient to reduce the pinning of the SKL to the underlying crystalline lattice, …
Effects Of Long-Range Tip-Sample Interaction On Magnetic Force Imaging: A Comparative Study Between Bimorph Driven System And Electrostatic Force Modulation, Byung I. Kim
Physics Faculty Publications and Presentations
Magnetic force microscopy (MFM) using electrostatic force modulation has been designed and developed to avoid the drawbacks of the bimorph driven system. The bimorph driven system has poor frequency response and overlap of the topographic features on magnetic structures of the MFM images. In the electrostatic force modulation system, the amplitude increases in the noncontact regime as the tip approaches due to the capacitive coupling between tip and sample. MFM using electrostatic force modulation has been applied to observe maze-like stripe domain structures on a CoCr film. The contrast mechanism and imaging stability of MFM using electrostatic force modulation are …
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 …
Simulating The Maximum Domain Wall Speed In A Magnetic Nanowire, Andrew Kunz
Simulating The Maximum Domain Wall Speed In A Magnetic Nanowire, Andrew Kunz
Physics Faculty Research and Publications
The dynamics of domain wall motion in permalloy nanowires have been simulated utilizing the Landau-Lifshitz-Gilbert (LLG) equation of motion. The simulation results are presented in terms of the domain wall speed for ranges of the Gilbert damping parameter alpha and nanowire width. The maximum domain wall speed is independent of alpha. The speed of the domain wall can be increased by increasing the nanowire width, but this lowers the critical field. For applied fields below the critical field, the wall moves uniformly along the wire and the speed of the wall increases with increases in the driving field. This behavior …
Micromagnetic Simulations On The Dependence Of Gilbert Damping On Domain Wall Velocities In Magnetic Nanowires, Andrew Kunz, B. Kastor
Micromagnetic Simulations On The Dependence Of Gilbert Damping On Domain Wall Velocities In Magnetic Nanowires, Andrew Kunz, B. Kastor
Physics Faculty Research and Publications
he dependence of damping on domain wall motion and velocity in Permalloy nanowires is presented. The domain wall motion in isolated two micron long Permalloy nanowires, with a rectangular cross-section 10 nm thick and 100 nm wide, is simulated using the Landau-Lifshitz Gilbert (LLG) simulation.Interpreting LLG dynamics can be difficult due to the dependence of the results on the Gilbert damping parameter alpha. The Walker model also predicts the critical field and domain wall velocity as a function of alpha. For these combined reasons the dependence of the domain wall speeds on the damping parameter is explored.
Magnetic Domain Structures In As-Quenched And Annealed Fe_{78}B_{13}Si_9 Metallic Glass Ribbons, Yücel Bi̇rol
Magnetic Domain Structures In As-Quenched And Annealed Fe_{78}B_{13}Si_9 Metallic Glass Ribbons, Yücel Bi̇rol
Turkish Journal of Physics
Among various soft magnetic materials, ferromagnetic glasses are superior to their crystalline counterparts as they possess no magnetocrystalline anisotropy owing to a non-crystalline structure. However, ferromagnetic glasses carry residual stresses and thus anisotropies of magnetostrictive origin in the as-quenched state. These stresses have an adverse effect on the magnetic softness and should be relieved in order to improve magnetic performance, particularly in magnetostrictive alloys. In the present work, the domain structures of Fe$_{78}$B$_{13}$Si$_9$ metallic glass, a highly magnetostrictive alloy, are characterized in the as-quenched and annealed states. The annealing treatments were carried out over a wide temperature range extending from …