Magnetic Skyrmions can be considered as localized vortexlike spin textures which are topologically protected in continuous systems. Because of their stability, their small size, and the possibility to move them by low electric currents, they are promising candidates for spintronic devices. Without changing the topological charge, it is possible to create Skyrmion-anti-Skyrmion pairs. We derive a Skyrmion equation of motion which reveals how spin-polarized charge currents create Skyrmion-anti-Skyrmion pairs. It allows us to identify general prerequisites for the pair creation process. We corroborate these general principles by numerical simulations. On a lattice, where the concept of topological protection has to be replaced by that of a finite energy barrier, the anti-Skyrmion partner of the pairs is annihilated and only the Skyrmion survives. This eventually changes the total Skyrmion number and yields a new way of creating and controlling Skyrmions.

We investigate the influence of the Jahn-Teller distortion and a direct antiferromagnetic moment coupling as extensions to a two-band Kondo lattice model for the magnetic and electronic properties of manganites. Those are calculated self-consistently via an interpolating self-energy model and a modified Ruderman-Kittel-Kasuya-Yosida technique using finite Hund coupling and quantum spins. We found that both effects are essential to achieve realistic Curie temperatures if we regard intraband Coulomb repulsion. Using reliable model parameters we got results which are in very good agreement with experimental data in the whole ferromagnetic doping range. In the calculated phase diagram there are ferromagnetic metal to paramagnetic insulator transitions, accompanied by a colossal magnetoresistance behavior. To improve the comparability of the measured behavior of the resistivity with the calculated one, we have to switch on interband Coulomb correlations.

Topologically distinct magnetic structures like skyrmions, domain walls, and the uniformly magnetized state have multiple applications in logic devices, sensors, and as bits of information. One of the most promising concepts for applying these bits is the racetrack architecture controlled by electric currents or magnetic driving fields. In state-of-the-art racetracks, these fields or currents are applied to the whole circuit. Here, we employ micromagnetic and atomistic simulations to establish a concept for racetrack memories free of global driving forces. Surprisingly, we realize that mixed sequences of topologically distinct objects can be created and propagated over far distances exclusively by local rotation of magnetization at the sample boundaries. We reveal the dependence between chirality of the rotation and the direction of propagation and define the phase space where the proposed procedure can be realized. The advantages of this approach are the exclusion of high current and field densities as well as its compatibility with an energy-efficient three-dimensional design.

We study the effects of spin-orbit interaction (SOI) on the current-induced motion of a magnetic (Bloch) domain wall in ultrathin ferromagnetic nanowires. The conspiracy of spin relaxation and SOI is shown to generate a strong nonequilibrium Rashba field, which can dominate even for weak SOI. This field causes intricate spin precession and a transition from translatory to oscillatory wall dynamics with increasing SOI. We show that current pulses of different lengths can be used to efficiently control the domain wall motion.

We investigate the current-induced motion of ferromagnetic domain walls in presence of a Rashba spin-orbit interaction of the itinerant electrons. We show how a Rashba interaction can stabilize the domain wall motion, such that the Walker breakdown is shifted to larger current densities. The Rashba spin-orbit interaction creates a field-like contribution to the spin torque, which breaks the symmetry of the system and modifies the internal structure of the domain wall. Moreover, it can induce an additional switching of the chirality of the domain wall for sufficiently strong Rashba interactions. This allows one to choose the desired chirality by the choosing the direction of the applied spin-polarized current. Both the suppression of the Walker breakdown and the chirality switching affect the domain wall velocity significantly. This is even more pronounced for short current pulses, where an additional domain wall drift in either positive or negative direction appears after the pulse ends. By this, we can steer the final position of the domain wall. This mechanism may help to overcome the current limitations of the domain wall motion due to the Walker breakdown which occurs for rather low current densities in systems without a Rashba spin-orbit interaction.