Magnetoresistance of atomic structures studied with a Scanning Tunneling Microscope
In this thesis spin-dependent properties of adsorbates placed in different magnetic environments are investigated using a low-temperature scanning tunneling microscope. Spin-polarized currents and anisotropic magnetoresistance (AMR) are studied for single atoms and atomic structures adsorbed on a ferro- magnetic Fe bilayer on W(110). This layer, thanks to its out-of-plane and in-plane magnetized domains and domain walls, respectively, allows to study equivalent adsorbates in different magnetic environments without the need for an external magnetic field. Three different experiments on spin-properties of atomic structures are briefly introduced in the following. Using spin-polarized tips, the energy and distance dependence of the spin-polarized current of single Ir atoms is investigated. Non-magnetic tips are employed to investigate the effect of spin-orbit coupling (SOC) on the differential conductance of artificially built Pb dimers and on the conductance of single atoms that are contacted with the STM tip. The last two effects are linked to AMR, which describes the SOC mediated dependence of the electrical resistance on the magnetization direction.