Fermi liquid instabilities and superconductivity near quantum critical points in f-electron materials

ABSTRACTRecent experiments on single crystals of the compounds CeRh1−xCoxIn5 and PrOs4Sb12 are briefly reviewed. The temperature-composition (T-x) phase diagram of the heavy fermion pseudoternary system CeRh1−xCoxIn5, delineating the regions in which superconductivity, antiferromagnetism, and the coexistence of these two phenomena occur, has been established. Entropy vs x isotherms and residual resistivity vs x plots exhibit peaks near the critical concentration xcr ≈ 0.8 at which the Néel temperature appears to vanish (quantum critical point). The filled skutterudite compound PrOs4Sb12 exhibits unconventional superconductivity below Tc = 1.85 K that involves heavy fermion quasiparticles with an effective mass m* ≈ 50 me, where me is the mass of the free electron. The unconventional superconducting state appears to consist of several distinct superconducting phases and to break time reversal symmetry. A high field ordered phase occurs below ∼ 1 K and between ∼ 4.5 T and ∼ 15 T that appears to be associated with quadrupolar order. The heavy fermion state and superconductivity in PrOs4Sb12 may originate from the interaction between Pr3+ electric quadrupole moments and the charges of the conduction electrons. When Ru is substituted for Os in PrOs4Sb12, a minimum in Tc occurs at Pr(Os0.4Ru0.6)4Sb12, suggesting a competition between two types of superconductivity.

Download Full-text

Dissipation-driven Strange Metal Behavior

10.21203/rs.3.rs-733414/v1 ◽

2021 ◽

Author(s):

Marco Grilli ◽

Sergio Caprara ◽

Carlo Di Castro ◽

Giovanni Mirarchi ◽

Goetz Seibold

Keyword(s):

Fermi Liquid ◽

Heavy Fermion ◽

Quantum Critical Point ◽

Isotropic Scattering ◽

Metallic Behavior ◽

Quantum Critical Points ◽

Superconducting Cuprates ◽

Dynamical Fluctuations ◽

Quantum Critical ◽

Temperature Resistivity

Abstract Anomalous metallic properties are often observed in the proximity of quantum critical points, with violation of the Fermi Liquid paradigm. We propose a scenario where, near the quantum critical point, dynamical fluctuations of the order parameter with finite correlation length mediate a nearly isotropic scattering among the quasiparticles over the entire Fermi surface. This scattering produces an anomalous metallic behavior, which is extended to the lowest temperatures by an increase of the damping of the fluctuations. We phenomenologically identify one single parameter ruling this increasing damping when the temperature decreases, accounting for both the linear-in-temperature resistivity and the seemingly divergent specific heat observed, e.g., in high-temperature superconducting cuprates and some heavy-fermion metals

Download Full-text

Dissipation-driven strange metal behavior

Communications Physics ◽

10.1038/s42005-021-00786-y ◽

2022 ◽

Vol 5 (1) ◽

Author(s):

Sergio Caprara ◽

Carlo Di Castro ◽

Giovanni Mirarchi ◽

Götz Seibold ◽

Marco Grilli

Keyword(s):

Fermi Liquid ◽

Heavy Fermion ◽

Quantum Critical Point ◽

Isotropic Scattering ◽

Metallic Behavior ◽

Quantum Critical Points ◽

Superconducting Cuprates ◽

Dynamical Fluctuations ◽

Quantum Critical ◽

Temperature Resistivity

AbstractAnomalous metallic properties are often observed in the proximity of quantum critical points, with violation of the Fermi Liquid paradigm. We propose a scenario where, near the quantum critical point, dynamical fluctuations of the order parameter with finite correlation length mediate a nearly isotropic scattering among the quasiparticles over the entire Fermi surface. This scattering produces a strange metallic behavior, which is extended to the lowest temperatures by an increase of the damping of the fluctuations. We phenomenologically identify one single parameter ruling this increasing damping when the temperature decreases, accounting for both the linear-in-temperature resistivity and the seemingly divergent specific heat observed, e.g., in high-temperature superconducting cuprates and some heavy-fermion metals.

Download Full-text

Possible quantum critical behavior revealed by the critical current density of hole doped high-Tc cuprates in comparison to heavy fermion superconductors

Scientific Reports ◽

10.1038/s41598-019-51467-4 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 1

Author(s):

S. H. Naqib ◽

R. S. Islam

Keyword(s):

Critical Current Density ◽

Copper Oxide ◽

Critical Point ◽

Critical Current ◽

Current Density ◽

Heavy Fermion ◽

Quantum Critical Point ◽

Oxide Superconductors ◽

Copper Oxide Superconductors ◽

Quantum Critical

Abstract The superconducting critical current density, Jc, in hole doped cuprates show strong dependence on the doped hole content, p, within the copper oxide plane(s). The doping dependent Jc mainly exhibits the variation of the intrinsic depairing critical current density as p is varied. Jc(p) tends to peak at p ~ 0.185 in copper oxide superconductors. This particular value of the hole content, often termed as the critical hole concentration, has several features putative to a quantum critical point (QCP). Very recently, the pressure dependences of the superconducting transition temperature (Tc) and the critical current (Ic) in pure CeRhIn5 and Sn doped CeRhIn5 heavy fermion compounds have been reported (Nature Communications (2018) 9:44, 10.1038/s41467-018-02899-5). The critical pressure demarcates an antiferromagnetic quantum critical point where both Tc and Ic are maximized. We have compared and contrasted this behavior with those found for Y1−xCaxBa2Cu3O7−δ in this brief communication. The resemblance of the systematic behavior of the critical current with pressure and hole content between heavy fermion systems and hole doped cuprates is significant. This adds to the circumstantial evidence that quantum critical physics probably plays a notable role behind the unconventional normal and superconducting state properties of copper oxide superconductors.

Download Full-text

Singular charge fluctuations at a magnetic quantum critical point

Science ◽

10.1126/science.aag1595 ◽

2020 ◽

Vol 367 (6475) ◽

pp. 285-288 ◽

Cited By ~ 9

Author(s):

L. Prochaska ◽

X. Li ◽

D. C. MacFarland ◽

A. M. Andrews ◽

M. Bonta ◽

...

Keyword(s):

Optical Conductivity ◽

Heavy Fermion ◽

Molecular Beam ◽

Cuprate Superconductors ◽

Quantum Critical Point ◽

Charge Fluctuations ◽

Quantum Matter ◽

Temperature Scaling ◽

Landau Quantum ◽

Quantum Critical

Strange metal behavior is ubiquitous in correlated materials, ranging from cuprate superconductors to bilayer graphene, and may arise from physics beyond the quantum fluctuations of a Landau order parameter. In quantum-critical heavy-fermion antiferromagnets, such physics may be realized as critical Kondo entanglement of spin and charge and probed with optical conductivity. We present terahertz time-domain transmission spectroscopy on molecular beam epitaxy–grown thin films of YbRh2Si2, a model strange-metal compound. We observed frequency over temperature scaling of the optical conductivity as a hallmark of beyond-Landau quantum criticality. Our discovery suggests that critical charge fluctuations play a central role in the strange metal behavior, elucidating one of the long-standing mysteries of correlated quantum matter.

Download Full-text