AVS 51st International Symposium
    Magnetic Interfaces and Nanostructures Wednesday Sessions
       Session MI-WeA

Paper MI-WeA9
Momentum Transfer in Exchange Bias Systems of the Type F/af/aaf

Wednesday, November 17, 2004, 4:40 pm, Room 304A

Session: Exchange Coupling, Surfaces, and Interfaces
Presenter: R. Mattheis, IPHT, Germany
Authors: R. Mattheis, IPHT, Germany
K. Steenbeck, IPHT, Germany
Correspondent: Click to Email
In F/AF exchange bias systems (F ferromagnet, AF antiferromagnet) momentum is transferred from the F film to the AF lattice by coupling via the AF interface net moment and the AF anisotropy. To study the dynamics of the AF lattice during rotation of the F layer magnetisation we sandwiched the F/AF system at the free AF side by a completely symmetric artificial antiferromagnet (AAF) of the kind CoFe/0.8 nm Ru/CoFe. At not too high magnetic field strength this AAF acts, due to its own coercivity and vanishing magnetic net moment, as a fixed spin system coupled at the opposite side of the AF. By means of torquemetry at 10K and 300K the rotational loss and exchange bias strength was determined for different AF thickness t. We found: a) The AAF can fix the AF spin system also at very low thickness t where K is zero. At this thickness exchange bias is found in F/AF system coupled to an AAF but not in the pure F/AF system. b) Fixing of the AF spins by coupling an AAF leads to a drastically reduction of the rotational losses in the AF and rotational anisotropy at a thickness where both where maximum without an AAF. The results show that overcoming the limited anisotropy in very thin AF films is possible by their coupling to an AAF. From the thickness dependence of the observed effects a deeper inside of the exchange bias phenomena is obtained and will be discussed in more detail.