Hall effect in quantum critical charge-cluster glass

Upon doping, cuprates undergo a quantum phase transition from an insulator to a d-wave superconductor. The nature of this transition and of the insulating state is vividly debated. Here, we study the Hall effect in La2-xSrxCuO4 (LSCO) samples doped near the quantum critical point at x ∼ 0.06. Dramatic fluctuations in the Hall resistance appear below TCG ∼ 1.5 K and increase as the sample is cooled down further, signaling quantum critical behavior. We explore the doping dependence of this effect in detail, by studying a combinatorial LSCO library in which the Sr content is varied in extremely fine steps, Δx ∼ 0.00008. We observe that quantum charge fluctuations wash out when superconductivity emerges but can be restored when the latter is suppressed by applying a magnetic field, showing that the two instabilities compete for the ground state.

Download Full-text

Magnetic field enhancement of the Hall effect anomalies in quantum critical point CeCu5.9Au0.1

Physica B Condensed Matter ◽

10.1016/j.physb.2007.10.355 ◽

2008 ◽

Vol 403 (5-9) ◽

pp. 1268-1269 ◽

Cited By ~ 3

Author(s):

D.N. Sluchanko ◽

V.V. Glushkov ◽

S.V. Demishev ◽

O.D. Chistyakov ◽

N.E. Sluchanko

Keyword(s):

Magnetic Field ◽

Hall Effect ◽

Critical Point ◽

Quantum Critical Point ◽

Field Enhancement ◽

Quantum Critical ◽

Magnetic Field Enhancement

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

DOES THE HEAVY ELECTRON MAINTAIN ITS INTEGRITY AT QUANTUM CRITICAL POINT?

International Journal of Modern Physics B ◽

10.1142/s0217979202013407 ◽

2002 ◽

Vol 16 (20n22) ◽

pp. 2991-2991

Author(s):

P. COLEMAN

Keyword(s):

Critical Point ◽

Density Wave ◽

Quantum Critical Point ◽

Spin Density Wave ◽

Electron Mass ◽

Heavy Electron ◽

Heavy Fermion Materials ◽

Quantum Critical ◽

Composite Nature ◽

Quantum Critical Behavior

This talk will 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. Is the quantum critical point merely a case of electron diffraction off a quantum critical spin density wave, or does it involve a fundamental break-down in the composite nature of the heavy electron place at the quantum critical point? We discuss the nature of the critical langrangian and show that the Hall constant changes continuously in the first scenario, but may "jump" discontinuously at a quantum critical point where the composite character of the electron quasiparticles changes.

Download Full-text