Investigation and control of domain walls and their interaction with spin-polarized currents in nanoscale ferromagnets

• Applicant: Professor Dr. Mathias Kläui
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2007 to 2012
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 46691129

In this project the interplay between magnetic domain walls and spin-polarized currents will be investigated using a range of experiments. Domain Wall quasi particles exhibit novel physical effects when a relative movement between the domain wall and the spin-polarized charge carriers occurs. Spin-polarized currents can be scattered from domain walls and large current densities can displace and transform the walls (current-induced domain wall motion due to spin transfer torque). To understand the spin torque effect and validate the present contradicting theories, dynamic and low temperature experiments are proposed that allow for the first time the unambiguous determination of the non-adiabaticity of the carrier transport and to probe current-induced eigenmodes and microwave excitations. The inverse effect, namely a voltage that occurs when a domain wall moves along a wire (spin motive force) has only been predicted theoretically and it will be tested for experimentally. Finally the experiments will be extended from the well-known NiFe alloys to exciting other materials, where larger effects are expected, such as doped 3d metals, alloys of rare earth compounds and other highly spin-polarized materials classes. This will yield the details of the interaction between the spin - polarized currents and the magnetization, which in many materials is not so far well understood and the validity and limits of the presently used s-d exchange model will be tested.

• DFG Programme: Research Grants
• International Connection: Switzerland