0854781_Plummer

1. New Correlated Electron Materials in the Rare EarthsWard E. Plummer, Louisiana State University & Agricultural and Mechanical College, DMR 0854781 Highly correlated electron behavior in rare earth intermetallic compounds leads in many cases to interesting superconductors. The rare earth Nd has well localized magnetic f-electrons and is not expected to show highly correlated electronic behavior, yet the specific heat (Cmag/T) divided by temperature shown above right and the low temperature electrical resistivity of Nd dissolved in the cubic simple metal LaB6 shown below right have the characteristics of strongly correlated electronic Kondo behavior. The speculation is that the highly symmetric crystalline environment of the Nd in LaB6 gives an f-electron ground state with large degrees of freedom which scatter conduction electrons in unexpected ways, resulting in increased electronic mass at low temperature. This expands the phase space of highly correlated electron materials in a new direction with the potential for new classes of such materials. This work has been done in collaboration with J. Stankiewicz and M. Evangelisti. .

2. New Correlated Electron Materials in the Rare EarthsWard E. Plummer, Louisiana State University & Agricultural and Mechanical College, DMR 0854781 We train both undergraduate and graduate students, foreign visiting students, postdoctoral fellows and foreign visitors in the synthesis and physical property characterization of materials and in single crystal growth. We have also developed new high signal to noise amplifiers for electronic investigation of gap structure in correlated electron materials, as well as software for interfacing with standard Quantum Design cryogenic equipment in wide use, allowing for integrating external electronics with their functioning system. The software programs and electronic designs are freely available and useful to a broad range of users. The above figure compares the noise output of our design current amplifier (green and red) with a high quality commercial amplifier (blue and black), without and with a 1nF input capacitor.