Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

MA: Magnetismus

MA 33: Spin-Dynamics, Magnetization Reversal III

MA 33.6: Vortrag

Donnerstag, 30. März 2006, 16:30–16:45, HSZ 403

Bloch line generation in cross-tie walls by fast magnetic field pulses — •Andreas Neudert, Jeffrey McCord, Rudolf Schäfer, and Ludwig Schultz — IFW Dresden, Postfach 270116, 01171 Dresden

In ferromagnetic films with an intermediate thickness of 30 to 90 nm cross-tie walls are observed. They consist of a sequence of circular and cross Bloch lines (also called vortex and antivortex) that are connected by 90^∘ Neel walls. Additional 90^∘ Neel walls emerge from the cross Bloch lines and form the "legs" of the cross-tie wall. We investigated the influence of a pulsed magnetic field (amplitude 400 A/m, width 1.2 ns) applied perpendicular to the wall plane onto a constrained cross-tie wall in a 80 µm x 160 µm permalloy rectangle of 50 nm thickness. The equilibrium cross-tie spacing of about 15 µm is reached after demagnetizing the sample with a magnetic ac-field. By applying the pulsed magnetic field with a repetition rate of 23 MHz additional Bloch lines are created and the cross-tie spacing decreases to about 5 µm. This Bloch line generation is not triggered by the repetition rate of the pulsed magnetic field as shown by using a low repetition rate pulse train of 0.2 Hz but by the fast rise time of the field pulses. A comparison with micromagnetic calculations will be given.