Domain-wall oscillations studies by time-resolved soft x-ray mircorscopy
- Resource Type
- Conference
- Authors
- Source
- Conference: 20th Interntional colloquium on magnetic films and surfaces, Berlin, Germany, July 20-24, 2009
- Subject
- 36 ADVANCED LIGHT SOURCE
AMPLITUDES
GEOMETRY
MAGNETIZATION
MEMORY DEVICES
MICROSCOPES
MICROSCOPY
NANOSTRUCTURES
OSCILLATIONS
PERMALLOY
PHASE SPACE
PROBES
RESOLUTION
SPATIAL RESOLUTION
VELOCITY
SOFT X RADIATION
- Language
- English
Fast magnetization dynamics in the micro- and nanometer regime are an interesting field of research. On these length scales magnetic structures can be designed to contain a single vortex or a single domain wall. Both size and speed of these patterns are of great interest in todays research for prospective non-volatile data storage devices. Especially the possibility to move domain-walls by spin-polarized current gained a lot of interest. Magnetic configurations can be imaged by soft X-ray magnetic microscopy with a spatial resolution down to 15 nm. By a stroboscopic pump and probe measurement scheme a temporal resolution below 100 ps is achieved. This provides the opportunity to directly image changes in magnetic domains and domain-wall motion. We image oscillations of a single domain wall in a confining potential in time steps of 200 ps by time resolved X-ray microscopy at the full-field soft X-ray transmission microscope at the Advanced Light Source in Berkeley (beamline 6.1.2). Domain walls are prepared in permalloy nanostructures with a restoring potential. The oscillation of a 180{sup o} domain wall is triggered by nanosecond current pulses. The spin-polarized current and the accompanying Oersted field can contribute to the motion of the wall. By analysis of the distinct domain-wall dynamics the dominant contribution is determined. In our geometry the motion of the wall is determined by the Oersted field although the spin-polarized current directly flows through the ferromagnetic structure. An analytical model of a rigid particle precisely describes the domain-wall motion. Oscillations are studied for different pulse length and amplitudes. From the observed oscillations we extract the driving force, the confining potential, and the domain-wall mass. Nonharmonic terms determine the motion of the wall. The influence of the nonharmonic potential is studied by looking at various phase spaces of the domain-wall motion.