Spin manipulation using magnetic stray fields

We are investigating the possibility to manipulate local electron spins using the magnetic stray field from patterned ferromagnetic structures. The magnetic stray field is typically very inhomogeneous. A field strength of more than one Tesla can be achieved at the surface of a ferromagnetic metal, and the field decays quickly on a distance comparable to the dimension of the ferromagnetic structure. This makes stray fields suitable for addressing local electron spins.

We have tested this idea by patterning stripes of Fe on a InGaAs quantum well. A magnetic field is applied perpendicularly to the stripes and in the plane of the quantum well. This magnetizes the stripes, which then generate a magnetic stray field. By optically exciting electron spins in the quantum well between the stripes and by monitoring the subsequent precession of these electron spins, we can evaluate the strength of the magnetic stray field [1].

 References