4f Quantum Criticality: In Search for Model Systems
| Date/Time: | Monday, 19 Oct 2015 from 4:10 pm to 5:00 pm |
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| Location: | Physics 0003 |
| Phone: | 515-294-5441 |
| Channel: | College of Liberal Arts and Sciences |
| Actions: | Download iCal/vCal | Email Reminder |
A brief overview of our recent studies of quantum criticality in 4f-based intermetallics will be given.
Ytterbium-based heavy fermion systems that could be tuned to the quantum critical point by application of magnetic field have been limited to relatively few examples. In the first part of the talk magnetic field induced quantum criticality in two stoichiometric compounds, hexagonal YbAgGe and cubic YbBiPt will be examined. Whereas the former exhibits reach and complex H - T phase diagram with a number of magnetic phases, the latter has a fragile, antiferromagnetic, SDW-like ground state. Transport and thermodynamic measurements in both compounds indicate existence of a crossover magnetic field associated with QCP (possibly associated with changes in the Fermi surface at the QCP). Both materials clearly show a non-Fermi liquid region adjacent to QCP. Position of YbAgGe and YbBiPt on a global phase diagram for heavy fermions that combines effects of Kondo coupling and magnetic frustration will be discussed.
Pressure induced quantum criticality in the YbTM2Zn20 (in particular, YbFe2Zn20) will be addressed in the second part of the talk, followed by presentation of the substitutional study in the Ce1-xLaxCu2Ge2 family that shows remarkably robust and correlated coherence and antiferromagnetism.