Current-induced resonance and mass determination of a single magnetic domain wall

Abstract

A magnetic domain wall (DW) is a spatially localized change of magnetization configuration in a magnet. This topological object has been predicted to behave at low energy as a composite particle with finite mass. This particle will couple directly with electric currents as well as magnetic fields, and its manipulation using electric currents is of particular interest with regard to the development of high-density magnetic memories. The DW mass sets the ultimate operation speed of these devices, but has yet to be determined experimentally. Here we report the direct observation of the dynamics of a single DW in a ferromagnetic nanowire, which demonstrates that such a topological particle has a very small but finite mass of 6.6 x 10(-23) kg. This measurement was realized by preparing a tunable DW potential in the nanowire, and detecting the resonance motion of the DW induced by an oscillating current. The resonance also allows low-current operation, which is crucial in device applications; a DW displacement of 10 microm was induced by a current density of 10(10) A m(-2).

Electron Holography of Magnetic Materials

“…It has recently been demonstrated that spin-transfer effects associated with injected currents can be used to displace magnetic domain walls (Saitoh et al, 2004). This effect is of interest for the development of novel memory and logic devices based on domain-wall propagation (Allwood et al, 2002).…”

Current-driven magnetic domain wall motion and its real-time detection

“…In particular, the acceleration=deceleration behavior triggered a debate on the existence of DW mass. 36,37) From a technological aspect, high-speed DW motion of up to 100 m=s was obtained for a current density of 1.5 × 10 12 A=m 2 , 38) a comparable speed to that of existing hard disk drives (HDDs). Controlled DW motion using multiple current pulses was successfully demonstrated and a proofof-concept experiment for the operation of a 3-bit shift register was also reported.…”

Encoding Magnetic States in Monopole‐Like Configurations Using Superconducting Dots

“…Especially attractive are artificial monopole‐like defects because of their similarity to magnetic charges. They can be generated in spin ice materials or in the form of head‐to‐head domain walls in magnetic nanowires,5, 6, 7, 8, 9, 10, 11, 12 however controllable approaches to imprint and manipulate such spin structures are needed. Here we present a novel strategy for robustly encoding nontrivial magnetic states in artificial nanoscale hybrid systems, formed by a soft ferromagnetic (FM) thin film interacting with hard superconducting thin dots.…”

“…Geometrical frustration has been the main strategy to generate nontrivial, monopolar‐like defects and other exotic states in magnetic materials such as spin ice systems or magnetic nanowires 5, 6, 7, 8, 9, 10, 11, 12, 13, 14. Skyrmions and other topological structures are typically created by artificially adding extra interactions, such as Dzyaloshinskii–Moriya interaction,2 to the conventional magnetic energy.…”