We demonstrate through simulations the feasibility of using magnetically coupled nanometer-scale ferromagnetic dots for digital information processing. Microelectronic circuits provide the input and output of the magnetic nanostructure, but the signal is processed via magnetic dot-dot interactions. Logic functions can be defined by the proper placements of dots. We introduce a SPICE macromodel of interacting nanomagnets and use this tool to design and simulate the proposed nanomagnet logic units. This SPICE model allows us to simulate such magnetic information processing devices within the same framework as conventional electronic circuits.Index Terms-Magnetic memories, micromagnetic design, patterned magnetic media, quantum-dot cellular automata, single-domain approximation, SPICE macromodel.
Geometrically constrained magnetic domain walls (DWs) in magnetic nanowires can be manipulated at the nanometer scale. The inhomogeneous magnetic stray field generated by a DW can capture a magnetic nanoparticle in solution. On-chip nanomanipulation of individual magnetic beads coated with proteins is demonstrated through the motion of geometrically constrained DWs in specially designed magnetic nanoconduits fully integrated in a lab-on-a-chip platform
The dynamic spin modes observed in magnetic vortex structures are shown to depend strongly on the nature of the initial excitation by a transient pulse field. In submicrometer-sized Permalloy disks, when a uniform perpendicular transient field is used to perturb the magnetization, radial standing-wave modes are excited; whereas if an in-plane transient field is used, angular or azimuthal modes are formed. The existence of the vortex core is responsible for a frequency splitting of the azimuthal modes, as demonstrated through comparison to micromagnetic simulations of a ring geometry
The ultrafast thermal and mechanical dynamics of a two-dimensional lattice of metallic nanodisks has been studied by near infrared pump-probe diffraction measurements, over a temporal range spanning from 100 fs to several nanoseconds. The experiments demonstrate that, in these systems, a two-dimensional surface acoustic wave (2DSAW), with a wavevector given by the reciprocal periodicity of the array, can be excited by ∼120 fs Ti:sapphire laser pulses. In order to clarify the interaction between the nanodisks and the substrate, numerical calculations of the elastic eigenmodes and simulations of the thermodynamics of the system are developed through finite-element analysis. At this light, we unambiguously show that the observed 2DSAW velocity shift originates from the mechanical interaction between the 2DSAWs and the nano-disks, while the correlated 2DSAW damping is due to the energy radiation into the substrate.
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