Quantum criticality in the heavy-Fermion superconductor cerium-cobalt-indium.
Contributors: Taillefer, Louis (supervisor)
Published: 2005
Language: eng
Number of pages: 168
Subjects: Physics Theses
Description: The study of quantum phase transitions has received a large amount of attention owing to the fact that a range of anomalous properties appear to be linked to the occurrence of quantum fluctuations. CeCoIn5 is a recently discovered heavy-fermion metal with an unconventional superconducting state below Tc = 2.3 K and a range of properties unexplained by the conventional Fermi liquid theory of metals. As a member of the CeMIn5 family (where M = Co, Ir or Rh), the anomalous transport, magnetic and thermodynamics properties of CeCoIn5 are thought to arise from an antiferromagnetic instability which has yet to be identified.This study reports measurements of heat and charge transport in CeCoIn 5, as a function of temperature T, magnetic field  H and orientation of current J with respect to the crystal axes, which have unearthed a host of incredible properties. These include the identification of a field-tuned quantum critical point (QCP) which coincides with the upper critical field of the superconducting state at  Hc2 = 5 T. As evidenced by divergences of the T2 coefficients of both electrical and thermal resistivities in the field-induced Fermi liquid state, the nature of this QCP is further elucidated by the observed relation between Delta H/T scaling and an anomalous T2/3 dependence of resistivity in the high-field non-Fermi liquid regime of  J &perp; [001] transport. Additional measurements of antiferromagnetic CeRhIn5 were also performed in order to shed light on the similarities and differences throughout this series of compounds.As a function of current orientation, qualitatively different behaviour is observed both in temperature and field dependences of transport. Whereas the temperature dependence of resistivity evolves with field for  J &perp; [001] transport, it remains linear in temperature for the  J 
Notes: Thesis (Ph.D.)--University of Toronto, 2005.

Electronic version licensed for access by U. of T. users.

Source: Dissertation Abstracts International, Volume: 66-06, Section: B, page: 3189.