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The spin-transfer torque between itinerant electrons and the magnetization in a ferromagnet is of fundamental interest for the applied physics community. To investigate the spin-transfer torque, powerful simulation tools are mandatory. We propose a micromagnetic standard problem including the spin-transfer torque that can be used for the validation and falsification of micromagnetic simulation tools. The work is based on the micromagnetic model extended by the spin-transfer torque in continuously varying magnetizations as proposed by Zhang and Li. The standard problem geometry is a permalloy cuboid of 100 nm edge length and 10 nm thickness, which contains a Landau pattern with a vortex in the center of the structure. A spin-polarized dc current density of 1012 A/m2 flows laterally through the cuboid and moves the vortex core to a new steady-state position. We show that the new vortex-core position is a sensitive measure for the correctness of micromagnetic simulators that include the spin-transfer torque. The suitability of the proposed problem as a standard problem is tested by numerical results from four different finite-difference and finite-element-based simulation tools. [ABSTRACT FROM AUTHOR]

It is shown that the current- and field-induced gyration of magnetic vortices and antivortices follows the analytical model of a two-dimensional harmonic oscillator. Quantities of the harmonic oscillator, i.e., resonance frequency, damping constant, gyration amplitude, and phase, can be linked to material parameters and sample dimensions. This description is useful for the investigation of vortex-switching and vortex-antivortex annihilation processes. [ABSTRACT FROM AUTHOR]

The theoretical foundation for a nonvolatile memory device based on magnetic vortices is presented. We propose a realization of a vortex random-access memory (VRAM) containing vortex cells that are controlled by alternating currents only. The proposed scheme allows to transfer the vortex into an unambiguous binary state regardless of its initial state within a subnanosecond time scale. The vortex handedness defined as the product of chirality and polarization as a bit representation allows direct mechanisms for reading and writing the bit information. The VRAM is stable at room temperature. [ABSTRACT FROM AUTHOR]