Ordering Phenomena in Transition Metal Oxides

Towards a theory of the non-Fermi liquid phase in MnSi   

Experiments in MnSi point towards the existence of an extended non-Fermi liquid phase. Motivated by recent neutron scattering experiments, which show an unexpected partial order, we discuss the role of topological defects and calculate the Goldstone modes in the system. The Goldstone modes can be overdamped but are not able to explain the experimentally observed resistivity. We furthermore argue that in the ordered phase, the interplay of various spin-orbit coupling effects leads to the formation of exponentially flat minibands on a sizeable fraction of the Fermi surface.