Instability of Walker Propagating Domain Wall in Magnetic Nanowires

Self Cite

106

Topological states of matter have been a subject of intensive studies in recent years because of their exotic properties such as the topologically protected edge and surface states. The initial studies were exclusively for electron systems. It is now known that topological states can also exist for other particles. Indeed, topologically protected edge states have already been found for phonons and photons. In spite of active searching for topological states in many fields, the studies in magnetism are relatively rare although topological states are apparently important and useful in magnonics. Here we show that the pyrochlore ferromagnets with the Dzyaloshinskii-Moriya interaction are intrinsic magnonic Weyl semimetals. Similar to the electronic Weyl semimetals, the magnon bands in a magnonic Weyl semimetal are nontrivially crossing in pairs at special points (called Weyl nodes) in momentum space. The equal energy contour around the Weyl nodes gives rise to the Fermi arcs on sample surfaces due to the topologically protected surface states between each pair of Weyl nodes. Additional Weyl nodes and Fermi arcs can be generated in lower energy magnon bands when an anisotropic exchange interaction is introduced.

Section: Introductionmentioning

confidence: 99%

Magnonic Weyl semimetal and chiral anomaly in pyrochlore ferromagnets

Wang

2017

Self Cite

106

“…In reciprocal mode, the breathing effect of TDWs' width naturally generates spin waves [37]. What's impressive is that even in traveling-wave mode, spin waves are also emitted and make Walker profile unstable [38]. However, due to the finite damping, spin waves in real materials will not survive too far from TDWs, thus saves the Walker solution.…”

Section: Introductionmentioning

confidence: 99%

Statics and field-driven dynamics of transverse domain walls in biaxial nanowires under uniform transverse magnetic fields

Lü

2016

In this work, we report analytical results on transverse domain wall (TDW) statics and field-driven dynamics in quasi one-dimensional biaxial nanowires under arbitrary uniform transverse magnetic fields (TMFs) based on the Landau-Lifshitz-Gilbert equation. Without axial driving fields, the static TDW should be symmetric about its center meanwhile twisted in its azimuthal angle distribution. By decoupling of polar and azimuthal degrees of freedom, an approximate solution is provided which reproduces these features to a great extent. When an axial driving field is applied, the dynamical behavior of a TDW is viewed as the response of its static profile to external excitations. By means of the asymptotic expansion method, the TDW velocity in traveling-wave mode is obtained, which provides the extent and boundary of the "velocity-enhancement" effect of TMFs to TDWs in biaxial nanowires. Finally numerical simulations are performed and strongly support our analytics.

“…One popular view [12,15,24] is to assume pinning as a trap potential well for DWs. However, the collective model, the base of the concept of the trap potential, may not be stable against spin-wave emission [25,26]. In general, a DW, whose structure is substantially deformed near a notch, is by no means a point particle, and it cannot be described by one coordinate like a DW center.…”

Section: Introductionmentioning

confidence: 99%

Domain wall pinning in notched nanowires

Yuan

Wang

2014

Self Cite

We theoretically and numerically study magnetic domain wall (DW) pinning at a notch in a magnetic nanowire. Based on the static DW equation, a general relationship between an external field and a DW structure for a given notch geometry is found. By estimating the field below which this relationship holds, we obtain the depinning field theoretically. Our theoretical estimate of the depinning field compares well with simulation results. Furthermore, our theory explains well why the depinning field of a transverse wall of one chirality is larger than that of the opposite chirality.