70 research outputs found
Phenomenology of current-induced skyrmion motion in antiferromagnets
We study current-driven skyrmion motion in uniaxial thin film
antiferromagnets in the presence of the Dzyaloshinskii-Moriya interactions and
in an external magnetic field. We phenomenologically include relaxation and
current-induced torques due to both spin-orbit coupling and spatially
inhomogeneous magnetic textures in the equation for the N\'eel vector of the
antiferromagnet. Using the collective coordinate approach we apply the theory
to a two-dimensional antiferromagnetic skyrmion and estimate the skyrmion
velocity under an applied DC electric current.Comment: 14 pages, 3 figures, 1 tabl
Driving spin chirality by electron dynamics in laser-excited antiferromagnets
Optical generation of complex spin textures is one of the most exciting
challenges of modern spintronics. Here, we uncover a distinct physical
mechanism for imprinting spin chirality into collinear magnets with short laser
pulses. By simultaneously treating the laser-ignited evolution of electronic
structure and magnetic order, we show that their intertwined dynamics can
result in an emergence of quasi-stable chiral states. We find that laser-driven
chirality does not require any auxiliary external fields or intrinsic
spin-orbit interaction to exist, and it can survive on the time scale of
nanoseconds even in the presence of thermal fluctuations, which makes the
uncovered mechanism relevant for understanding various optical experiments on
magnetic materials. Our findings open a new perspective at the interaction of
complex chiral magnetism with light.Comment: 5+5 pages and 4+15 figures with supplementary material
Topological-chiral magnetic interactions driven by emergent orbital magnetism
Two hundred years ago, Andr\'e-Marie Amp\`ere discovered that electric loops
in which currents of electrons are generated by a penetrating magnetic field
can interact with each other. Here we show that Amp\`ere's observation can be
transferred to the quantum realm of interactions between triangular plaquettes
of spins on a lattice, where the electrical currents at the atomic scale are
associated with a peculiar type of the orbital motion of electrons in response
to the non-coplanarity of neighbouring spins playing the role of a magnetic
field. The resulting topological orbital moment underlies the relation of the
orbital dynamics with the topology of the spin structure. We demonstrate that
the interactions of the topological orbital moments with each other and with
the spins of the underlying lattice give rise to a new class of magnetic
interactions topological chiral interactions which can dominate over
the celebrated Dzyaloshinskii-Moriya interaction, thus opening a path for the
realization of new classes of chiral magnetic materials with three-dimensional
magnetization textures such as magnetic hopfions
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