60 research outputs found

    Asymmetric Ferromagnetic Resonance, Universal Walker Breakdown, and Counterflow Domain Wall Motion in the Presence of Multiple Spin-Orbit Torques

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    We study the motion of several types of domain wall profiles in spin-orbit coupled magnetic nanowires and also the influence of spin-orbit interaction on the ferromagnetic resonance of uniform magnetic films. We extend previous studies by fully considering not only the field-like contribution from the spin-orbit torque, but also the recently derived Slonczewski-like spin-orbit torque. We show that the latter interaction affects both the domain wall velocity and the Walker breakdown threshold non-trivially, which suggests that it should be accounted in experimental data analysis. We find that the presence of multiple spin-orbit torques may render the Walker breakdown to be universal in the sense that the threshold is completely independent on the material-dependent Gilbert damping, non-adiabaticity, and the chirality of the domain wall. We also find that domain wall motion against the current injection is sustained in the presence of multiple spin-orbit torques and that the wall profile will determine the qualitative influence of these different types of torques (e.g. field-like and Slonczewski-like). In addition, we consider a uniform ferromagnetic layer under a current bias, and find that the resonance frequency becomes asymmetric against the current direction in the presence of Slonczewski-like spin-orbit coupling. This is in contrast with those cases where such an interaction is absent, where the frequency is found to be symmetric with respect to the current direction. This finding shows that spin-orbit interactions may offer additional control over pumped and absorbed energy in a ferromagnetic resonance setup by manipulating the injected current direction.Comment: 12 pages including 7 figure

    Tunable Supercurrent at the Charge Neutrality Point via Strained Graphene Junctions

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    We theoretically calculate the charge-supercurrent through a ballistic graphene junction where superconductivity is induced via the proximity-effect. Both monolayer and bilayer graphene are considered, including the possibility of strain in the systems. We demonstrate that the supercurrent at the charge neutrality point can be tuned efficiently by means of mechanical strain. Remarkably, the supercurrent is enhanced or suppressed relative to the non-strained case depending on the direction of this strain. We also calculate the Fano factor in the normal-state of the system and show how its behavior varies depending on the direction of strain.Comment: 7 Pages and 4 Figures. To Appear in Physical Review