Spinpolarisierte Rastertunnelmikroskopie an magnetischen Nanostrukturen: Fe/W(110)
Andre Kubetzka, Hamburg, 29.4.2002
In this work spinpolarized scanning tunneling microscopy and spectroscopy (SP-STM/-STS) is employed to investigate magnetic nanostructures and ultrathin films at low temperatures and in ultrahigh vacuum. The main subject is the system Fe/W(110), which, in the coverage regime of about two atomic layers Fe, exhibits a surprising complexity of magnetic domain structures. This complexity arises from the films' nanostructure, as well as from their intrinsic magnetic properties. SP-STM proves to be an ideal tool for characterisation, since structural, electronic, and magnetic properties can be investigated simultaneously on the nanometer scale and correlated directly.
Along with ferromagnetic tips, for the first time antiferromagnetic tips are employed, which, due to their vanishing stray field, solve the problem of an influence on the sample, and thereby enable the investigation of soft magnetic materials and superparamagnetic particles. Furthermore, it is shown that even nonmagnetic tips allow an imaging of domain walls, since the walls locally modify the electronic structure of the surface. Finally, an antiferromagnetic monolayer Mn/W(110) is imaged, which demonstrates that SP-STM has ultimately a resolution at the atomic scale.
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