How do Fermi liquids get heavy and die?

Abstract

We discuss non-Fermi liquid and quantum critical behavior in heavy fermion materials, focussing on the mechanism by which the electron mass appears to diverge at the quantum critical point. We ask whether the basic mechanism for the transformation involves electron diffraction off a quantum critical spin density wave, or whether a break-down in the composite nature of the heavy electron takes place at the quantum critical point. We show that the Hall constant changes continously in the first scenario, but may "jump" discontinuously at a quantum critical point where the composite character of the electron quasiparticles changes.

New hints on the origin of quantum criticality in CeCoIn5: A Hall effect study

“…The breakdown of scaling with increased pressure coincides with the suppression of the QCP [10], which suggests that the two are related. Note that our scaling formR H ¼ R H m f ðH=H 0 þ AT a Þ is in clear contrast with the DH=T type of scaling (with DH ¼ H À H QCP ) expected near a field tuned QCP at H QCP [1]. A similar scaling of the form…”

“…This occurs near a quantum critical point (QCP), corresponding to a T ¼ 0 phase transition between two different ground states. In this context, the question of whether the Fermi surface (FS) volume changes abruptly across the QCP has become a focus of attention in recent years [1]. The Hall effect is a particularly useful tool to address this issue.…”

Critical Kondo destruction and the violation of the quantum-to-classical mapping of quantum criticality

“…In Y bRh 2 Si 2 , multiple energy scales collapse at its field-tuned QCP and, moreover, the Fermi surface has been implicated to transition from large to small when the QCP is crossed from the paramagnetic side. These rich behaviors have led to the question as to whether and how the Kondo screening is affected as the system undergoes a magnetic phase change [11,12].…”

Pairing correlations near a Kondo-destruction quantum critical point

“…Spin-density-wave (SDW) QCPs are described in the Landau framework of order-parameter fluctuations [7]. The other class of QCPs goes beyond the Landau approach by invoking a critical destruction of the Kondo effect [8,9]. Distinctive features of this "local quantum criticality" include ω/T scaling in the spin susceptibility and the single-particle spectral function, vanishing of an additional energy scale, and a jump in the Fermi-surface volume.…”

“…This behavior is likely to have significant effects in lattice systems. Within C-EDMFT [15], the cluster pairing susceptibility determines the lattice pairing susceptibility, in such a way that the enhanced χ d may give rise to a pairing instability near a Fermi-surfacecollapsing QCP of a Kondo lattice [8,9]. As such, this would represent a new mechanism for superconductivity in the vicinity of antiferromagnetic order, and would be of considerable interest in connection with the superconductivity observed in the Ce-115 materials [37] and related heavy-fermion superconductors [38].…”