Low Energy Charge and Spin Excitations probed by NMR and Transport

• Applicant: Professor Dr. Bernd Büchner
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2007 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5470877

In this project, the electronic and magnetic degrees of freedom of the High Temperature Superconductors (HTSC) will be studied by means of Nuclear Magnetic Resonance (NMR) and transport measurements (Nernst effect, thermal transport, etc.). The investigation of the pseudogap and of spin and charge inhomogeneities will be the exploratory focus of this project. Both phenomena and their impact on superconductivity are unclear. We want to apply two complementary experimental methods – microscopic NMR and macroscopic transport measurements – to arrive at a comprehensive understanding of these two unusual phenomena and their impact on superconductivity. In particular, we wish to make use of the combination of these two different methods since both are sensitive to the above phenomena, despite the quantities measured by each method being completely different. Furthermore, no explicit comparison of results from the two methods currently exists, i.e. in our project we will be able to directly compare the results of both measurements on the same samples for the first time. Our project will be perfectly integrated within the Research Unit since NMR and transport measure electronic and magnetic low-energy excitations whereas the other experimental techniques of the Research Unit such as ARPES, Neutron scattering and the optical methods are sensitive to high-energy excitations.

• DFG Programme: Research Units
• Subproject of: FOR 538: Doping Dependence of Phase Transitions and Ordering Phenomena in Cuprate Superconductors
• Participating Persons: Dr. Hans-Joachim Grafe; Professor Dr. Christian Hemker-Heß