Partial magnetization reversal in a perpendicular exchange-biased [Pd∕Co]∕FeMn film through laser annealing

Abstract

Partial magnetization reversal on the perpendicular exchange-bias characteristics in the [Pd∕Co]×5∕FeMn bilayered and [Pd∕Co]×2∕Cu∕Co∕[Pd∕Co]×2∕FeMn spin valve thin films was investigated using laser. The hysteresis loops were measured using the extraordinary Hall effect and magneto-optical Kerr effect (MOKE). By increasing the output intensity of the laser, the exchange-bias fields in the [Pd∕Co]×5∕FeMn bilayered thin film were gradually changed from negative to positive. The distribution of partial magnetization reversal in the vicinity of the laser spot was measured by using MOKE. Although the magnetic moment of the pinned layer was gradually reversed by using laser annealing in the MOKE loops of the [Pd∕Co]×2∕Cu∕Co∕[Pd∕Co]×2∕FeMn spin valves’ structure, that of the free layer was not changed. When the pattern size was decreased to 5×5μm2, the direction of exchange biasing was fully reversed through laser annealing without distorting the hysteresis loop. All the patterned samples below 100×100μm2 have the same hysteresis loop, and the reversed loops were not distorted and reduced when laser annealing was used.

Polarized current changes the exchange bias in a current-in-plane spin valve

“…A survey of most of EB experiments on the magnetic field applied during field cooling from above the blocking temperature and thermal decay of EB under a magnetic field antiparallel to the pinning direction reveals that the heat treatment time is almost several tens of minutes [23][24][25]. In addition, laser annealing experiments on NiFe/FeMn films demonstrated that the energy required to reverse the EB was approximately 90-360 J [26,27]. However, the energy generated by the current pulse in our experiment was approximately 0.85-0.21 J, which is much lower than the energy required.…”

“…To date, many other post-deposition strategies have been used for EB tuning, such as electric field control [32][33][34], magnetic field control [35][36][37], ion irradiation [38,39], and laser annealing [26,27]. However, many of these approaches have disadvantages.…”