Dynamics of Dirac strings and monopole-like excitations in chiral magnets under a current drive

Abstract

Skyrmion lines in metallic chiral magnets carry an emergent magnetic field experienced by the conduction electrons. The inflow and outflow of this field across a closed surface is not necessarily equal, thus it allows for the existence of emergent monopoles. One example is a segment of skyrmion line inside a crystal, where a monopole and antimonopole pair is connected by the emergent magnetic flux line. This is a realization of Dirac string-like excitations. Here we study the dynamics of monopoles in chiral magnets under an electric current. We show that in the process of creation of skyrmion lines, skyrmion line segments are first created via the proliferation of monopoles and antimonopoles. Then these line segments join and span the whole system through the annihilation of monopoles. The skyrmion lines are destroyed via the proliferation of monopoles and antimonopoles at high currents, resulting in a chiral liquid phase. We also propose to create the monopoles in a controlled way by applying an inhomogenous current to a crystal. Remarkably, an electric field component in the magnetic field direction proportional to the current squared in the low current region is induced by the motion of distorted skyrmion lines, in addition to the Hall and longitudinal voltage. The existence of monopoles can be inferred from transport or imaging measurements.

6 pages and 5 figures

References in corpus (6)

• Spontaneous Skyrmion Ground States in Magnetic Metals
• Theory of current-driven motion of Skyrmions and spirals in helical magnets
• Long wavelength helimagnetic order and skyrmion lattice phase in Cu2OSeO3
• Thermally Driven Ratchet Motion of Skyrmion Microcrystal and Topological Magnon Hall Effect
• Electric field-induced Skyrmion distortion and giant lattice rotation in the magnetoelectric insulator Cu2OSeO3
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• Current-induced viscoelastic topological unwinding of metastable skyrmion strings
• Face centered cubic and hexagonal close packed skyrmion crystals in centro-symmetric magnets
• Emergent electromagnetism induced by topological defects created during magnetization reversal in nanowires
• Current-induced dynamics of skyrmion tubes in synthetic antiferromagnetic multilayers
• Electric transport in three-dimensional Skyrmion/monopole crystal
• Kelvin modes of a skyrmion line in chiral magnets and the associated magnon transport
• Solitary wave excitations of skyrmion strings in chiral magnets
• Ultrasonic elastic responses in monopole lattice
• Nonlinear dynamics of skyrmion strings
• Instability of magnetic skyrmion strings induced by longitudinal spin currents
• Synthetic half-integer magnetic monopole and single-vortex dynamics in spherical Bose-Einstein condensates
• Bulk and surface topological indices for a skyrmion string