Corwin Booth's Home Page
(invited talk for XAFS XI), J. Synchrotron Rad., 8, 191 (2000).
Abstract
Lanthanide and actinide intermetallic compounds display a wide range of
correlated-electron behavior, including ferromagnetism, antiferromagnetism,
nonmagnetic (Kondo) ground states, and so-called ``non-Fermi liquid'' (NFL)
behavior. The interaction between $f$ electrons and the conduction band is
a dominant factor in determining the ground state of a given system. However,
lattice disorder can create a distribution of interactions, generating unusual
physical properties. These properties may include NFL behavior in many
materials. In addition, lattice disorder can cause deviations from standard
Kondo behavior that is less severe than NFL behavior. We will review the
lattice disorder mechanism within a tight-binding model and present measurementsof the Yb$B$Cu$_4$ and UPd$_x$Cu$_{5-x}$ systems demonstrating the applicabilityof the model. These measurements indicate that while the Yb$B$Cu$_4$ system
appears to be well ordered, both site interchange and continuous bond-length
disorder occur in the UPd$_x$Cu$_{5-x}$ series. Nevertheless, the measured
bond-length disorder in UPdCu$_{4}$ does not appear to be enough to
explain the NFL properties simply with this Kondo disorder model.