Grading the magnetic anisotropy and engineering the domain wall dynamics in Fe-rich microwires by stress-annealing

We have studied the magnetic properties and domain wall dynamics in Fe-rich microwires subjected to stress-annealing. The hysteresis loops of Fe-rich microwires were considerably affected by stress-annealing. We obtained drastic decrease in coercivity and change in the character of hysteresis loops from rectangular to linear in stress-annealed Fe-rich microwires. For the wires after stress-annealing at variable temperatures we obtained a graded magnetic behavior with local hysteresis loops shapes and features (coercivity, remanent magnetization) changing along the sample length. In the samples subjected to local stress-annealing we created an artificial source of domain wall injection allowing the manipulation of domain wall dynamics. The observed stress-induced anisotropy could be related to the internal stress relaxation after annealing and the interplay of compressive "back-stresses" arisen after stress annealing and axial internal stresses.