26 research outputs found
Magnetic anisotropy by Rashba spin-orbit coupling in antiferromagnetic thin films
Magnetic anisotropy in an antiferromagnet (AFM) with inversion symmetry
breaking (ISB) is investigated. The magnetic anisotropy energy (MAE) resulting
from the Rashba spin-orbit and s-d type exchange interactions is determined for
two different models of AFMs. The global ISB model, representing the effect of
a surface, an interface, or a gating electric field, results in an easy-plane
magnetic anisotropy. In contrast, for a local ISB model, i.e., for a
noncentrosymmetric AFM, perpendicular magnetic anisotropy (PMA) arises. Both
results differ from the ferromagnetic case, in which the result for PMA depends
on the band structure and dimensionality. These MAE contributions play a key
role in determining the direction of the Neel order parameter in
antiferromagnetic nanostructures, and reflect the possibility of
electrical-field control of the Neel vector.Comment: 4 pages, 2 figure
Emergence of inductance and capacitance from topological electromagnetism
Topological electromagnetism owing to nontrivial momentum-space topology of
electrons in insulators gives rise to diverse anomalous magnetoelectric
responses. While conventional inductors and capacitors are based on classical
electromagnetism described by Maxwell's equations, here we show that
topological electromagnetism in combination with spin dynamics in magnets also
generates an inductance or a capacitance. We build a generic framework to
extract the complex impedance on the basis of topological field theory, and
demonstrate the emergence of an inductance or a capacitance in several
heterostructure setups. In comparison with the previously-studied emergent
inductances in metallic magnets, insulators highly suppress the power loss,
because of the absence of Joule heating. We show that the inductance from
topological electromagnetism is achieved at low current and high frequency, and
is also advantageous in its power efficiency, as characterized by the high
quality factor (Q-factor).Comment: 9 pages, 4 figures + Supplemental Information (4 pages
Spinmotive force due to motion of magnetic bubble arrays driven by magnetic field gradient
Interaction between local magnetization and conduction electrons is
responsible for a variety of phenomena in magnetic materials. It has been
recently shown that spin current and associated electric voltage can be induced
by magnetization that depends on both time and space. This effect, called
spinmotive force, provides for a powerful tool for exploring the dynamics and
the nature of magnetic textures, as well as a new source for electromotive
force. Here we theoretically demonstrate the generation of electric voltages in
magnetic bubble array systems subjected to a magnetic field gradient. It is
shown by deriving expressions for the electric voltages that the present system
offers a direct measure of phenomenological parameter that describes
non-adiabaticity in the current induced magnetization dynamics. This spinmotive
force opens a door for new types of spintronic devices that exploit the
field-gradient.Comment: accepted in Scientific Report