Strongly correlated electron systems are materials in which interactions between the electrons are very important and produce a variety of phenomena such as high-temperature superconductivity, unusual magnetic effects, or heavy Fermion behaviour (in which the electron mass appears to be much larger than that normally associated with a single electron). According to conventional theories of such systems, the strong interactions between f-electrons and conduction electrons (hybridization) result in the opening of a gap in both charge and spin channels. However, there are few experimental observations of such gaps. Inelastic neutron scattering (INS) is a unique technique and provides direct information on the spin gap energy as well as further details that are not accessible to other techniques such as optical measurements. Further, such studies provide important information about the microscopic mechanism of gap formation. Recently we have used INS to investigate spin gap formation in several heavy Fermion compounds such as CeRhAs. We have found a universal scaling relation between the spin gap energy and the temperature below which the electron hybridization occurs, giving us new insights into these materials.
DT Adroja (ISIS), J-G Park (SungKyunKwan University, South Korea), KA McEwen (University College London), K Shigetoh, T Sasakawa, T Takabatake (Hiroshima University, Japan)
Contact: Dr DT Adroja, Devashibhai.Adroja@stfc.ac.uk
Research date: December 2008
J. Optoelectronic and Advanced Materials 10 (2008) 1719; Physica B 378 (2006) 788