4,099 research outputs found
Spin Hall and Nernst effects of Weyl magnons
In this paper, we present a simple model of a three-dimensional insulating
magnetic structure which represents a magnonic analog of the layered electronic
system described in [Phys. Rev. Lett. {\bf 107}, 127205 (2011)]. In particular,
our model realizes Weyl magnons as well as surface states with a Dirac
spectrum. In this model, the Dzyaloshinskii-Moriya interaction is responsible
for the separation of opposite Weyl points in momentum space. We calculate the
intrinsic (due to the Berry curvature) transport properties of Weyl and
so-called anomalous Hall effect (AHE) magnons. The results are compared with
fermionic analogs.Comment: 9 pages, 5 figures, published versio
New method for determining the distances to certain extragalactic radio sources
The structural evolution of variable radio sources is examined in the Hedgehog model. It is shown that the time evolution of the angular separation of two components is described by the ellipse equation
Magnon spin Nernst effect in antiferromagnets
We predict that a temperature gradient can induce a magnon-mediated spin Hall
response in an antiferromagnet with non-trivial magnon Berry curvature. We
develop a linear response theory which gives a general condition for a Hall
current to be well defined, even when the thermal Hall response is forbidden by
symmetry. We apply our theory to a honeycomb lattice antiferromagnet and
discuss a role of magnon edge states in a finite geometry.Comment: 17 page
On the internal modes in sine-Gordon chain
We address the issue of internal modes of a kink of a discrete sine-Gordon
equation. The main point of the present study is to elucidate how the
antisymmetric internal mode frequency dependence enters the quasicontinuum
spectrum of nonlocalized waves. We analyze the internal frequency dependencies
as functions of both the number of cites and discreteness parameter and explain
the origin of spectrum peculiarity which arises after the frequency dependence
of antisymmetric mode returns back to the continuous spectrum at some nonzero
value of the intersite coupling.Comment: 5 pages, 3 figure
Chiral topological insulator of magnons
We propose a magnon realization of 3D topological insulator in the AIII
(chiral symmetry) topological class. The topological magnon gap opens due to
the presence of Dzyaloshinskii-Moriya interactions. The existence of the
topological invariant is established by calculating the bulk winding number of
the system. Within our model, the surface magnon Dirac cone is protected by the
sublattice chiral symmetry. By analyzing the magnon surface modes, we confirm
that the backscattering is prohibited. By weakly breaking the chiral symmetry,
we observe the magnon Hall response on the surface due to opening of the gap.
Finally, we show that by changing certain parameters the system can be tuned
between the chiral topological insulator (mcTI), three dimensional magnon
anomalous Hall (3D-mAH), and Weyl magnon phases.Comment: 6 page
Theory of magnon motive force in chiral ferromagnets
We predict that magnon motive force can lead to temperature dependent,
nonlinear chiral damping in both conducting and insulating ferromagnets. We
estimate that this damping can significantly influence the motion of skyrmions
and domain walls at finite temperatures. We also find that in systems with low
Gilbert damping moving chiral magnetic textures and resulting magnon motive
forces can induce large spin and energy currents in the transverse direction
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