Field-Driven Domain-Wall Dynamics in GaMnAs Films with Perpendicular Anisotropy

Alexandre Dourlat (1) , Vincent Jeudy (1) , Aristide Lemaître (2) , Catherine Gourdon (1)

1 INSP - Institut des Nanosciences de Paris
2 LPN - Laboratoire de photonique et de nanostructures

We combine magneto-optical imaging and a magnetic field pulse technique to study domain wall dynamics in a ferromagnetic (Ga,Mn)As layer with perpendicular easy axis. Contrary to ultrathin metallic layers, the depinning field is found to be smaller than the Walker field, thereby allowing for the observation of the steady and precessional flow regimes. The domain wall width and damping parameters are determined self-consistently. The damping, 30 times larger than the one deduced from ferromagnetic resonance, is shown to essentially originate from the non-conservation of the magnetization modulus. An unpredicted damping resonance and a dissipation regime associated with the existence of horizontal Bloch lines are also revealed.

Mots clés: Magnetic semiconductors; Domain walls and domain structure; Magnetic properties of monolayers and thin films; Kerr microscopy

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Alexandre Dourlat, Vincent Jeudy, Aristide Lemaître, Catherine Gourdon. Field-Driven Domain-Wall Dynamics in GaMnAs Films with Perpendicular Anisotropy. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2008, 78, pp.161303(R). ⟨10.1103/PhysRevB.78.161303⟩. ⟨hal-00308773⟩