Spectroscopic evidences of quantum critical charge fluctuations in cuprates

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.

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Hall effect in quantum critical charge-cluster glass

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1519630113 ◽

2016 ◽

Vol 113 (16) ◽

pp. 4284-4289 ◽

Cited By ~ 17

Author(s):

Jie Wu ◽

Anthony T. Bollinger ◽

Yujie Sun ◽

Ivan Božović

Keyword(s):

Hall Effect ◽

Ground State ◽

Quantum Critical Point ◽

Hall Resistance ◽

Charge Fluctuations ◽

Charge Cluster ◽

Quantum Critical ◽

Quantum Critical Behavior ◽

Quantum Charge ◽

D Wave

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.

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Time-domain pumping a quantum-critical charge density wave ordered material

Physical Review B ◽

10.1103/physrevb.94.115167 ◽

2016 ◽

Vol 94 (11) ◽

Cited By ~ 9

Author(s):

O. P. Matveev ◽

A. M. Shvaika ◽

T. P. Devereaux ◽

J. K. Freericks

Keyword(s):

Charge Density ◽

Time Domain ◽

Charge Density Wave ◽

Density Wave ◽

Critical Charge ◽

Quantum Critical

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Critical charge fluctuations in a pseudogap Anderson model

Physical Review B ◽

10.1103/physrevb.91.035118 ◽

2015 ◽

Vol 91 (3) ◽

Cited By ~ 5

Author(s):

Tathagata Chowdhury ◽

Kevin Ingersent

Keyword(s):

Anderson Model ◽

Charge Fluctuations ◽

Critical Charge

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THEORY OF CRITICAL CHARGE FLUCTUATIONS AND PSEUDOGAP FORMATION IN THE SINGLE-BAND HUBBARD MODEL

International Journal of Modern Physics B ◽

10.1142/s0217979200002466 ◽

2000 ◽

Vol 14 (25n27) ◽

pp. 3000-3005 ◽

Cited By ~ 1

Author(s):

ROBERTA CITRO ◽

MARIO MARINARO

Keyword(s):

Hubbard Model ◽

Density Wave ◽

Charge Ordering ◽

Single Band ◽

Electron Interaction ◽

Charge Fluctuations ◽

Effective Electron ◽

Critical Charge ◽

A Charge ◽

Precursor Effects

Within a single-band Hubbard model, treated by means of a strong-coupling approach based on a cumulant expansion, we investigate the existence of critical charge fluctuations (CCF) that could give rise to a phase separation (PS) or a charge density wave, by means of a Bethe-Salpeter equation for the vertex function in the particle-hole channel. We discuss the relevance of the precursor effects of charge ordering on the self-energy of the electrons and the non-Fermi liquid behavior arising from an effective electron-electron interaction.

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