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