scholarly journals Experimental observables near a nematic quantum critical point in the pnictide and cuprate superconductors

2008 ◽  
Vol 78 (13) ◽  
Author(s):  
Cenke Xu ◽  
Yang Qi ◽  
Subir Sachdev
Keyword(s):  
Critical Point ◽  
Cuprate Superconductors ◽  
Quantum Critical Point ◽  
Quantum Critical

scholarly journals Non-vanishing zero-temperature normal density in holographic superfluids

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Blaise Goutéraux ◽  
Eric Mefford
Keyword(s):  
Charge Density ◽  
Critical Point ◽  
Critical Exponents ◽  
Cuprate Superconductors ◽  
Quantum Critical Point ◽  
Dimensional System ◽  
Normal Density ◽  
Zero Temperature ◽  
Normal Flow ◽  
Quantum Critical

Abstract The low energy and finite temperature excitations of a d + 1-dimensional system exhibiting superfluidity are well described by a hydrodynamic model with two fluid flows: a normal flow and a superfluid flow. In the vicinity of a quantum critical point, thermodynamics and transport in the system are expected to be controlled by the critical exponents and by the spectrum of irrelevant deformations away from the quantum critical point. Here, using gauge-gravity duality, we present the low temperature dependence of thermodynamic and charge transport coefficients at first order in the hydrodynamic derivative expansion in terms of the critical exponents. Special attention will be paid to the behavior of the charge density of the normal flow in systems with emergent infrared conformal and Lifshitz symmetries, parameterized by a Lifshitz dynamical exponent z > 1. When 1 ≤ z < d + 2, we recover (z = 1) and extend (z > 1) previous results obtained by relativistic effective field theory techniques. Instead, when z > d + 2, we show that the normal charge density becomes non-vanishing at zero temperature. An extended appendix generalizes these results to systems that violate hyperscaling as well as systems with generalized photon masses. Our results clarify previous work in the holographic literature and have relevance to recent experimental measurements of the superfluid density on cuprate superconductors.

scholarly journals Tuning the charge density wave quantum critical point and the appearance of superconductivity in TiSe2

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Sangyun Lee ◽  
Tae Beom Park ◽  
Jihyun Kim ◽  
Soon-Gil Jung ◽  
Won Kyung Seong ◽  
...  
Keyword(s):  
Charge Density ◽  
Critical Point ◽  
Charge Density Wave ◽  
Density Wave ◽  
Quantum Critical Point ◽  
Quantum Critical

scholarly journals Lattice-shifted nematic quantum critical point in FeSe1−xSx

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
S. Chibani ◽  
D. Farina ◽  
P. Massat ◽  
M. Cazayous ◽  
A. Sacuto ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Critical Point ◽  
Degrees Of Freedom ◽  
Quantum Critical Point ◽  
Substantial Effect ◽  
Low Energy ◽  
Elastic Coupling ◽  
Superconducting Transition ◽  
Local Moments ◽  
Quantum Critical

AbstractWe report the evolution of nematic fluctuations in FeSe1−xSx single crystals as a function of Sulfur content x across the nematic quantum critical point (QCP) xc ~ 0.17 via Raman scattering. The Raman spectra in the B1g nematic channel consist of two components, but only the low energy one displays clear fingerprints of critical behavior and is attributed to itinerant carriers. Curie–Weiss analysis of the associated nematic susceptibility indicates a substantial effect of nemato-elastic coupling, which shifts the location of the nematic QCP. We argue that this lattice-induced shift likely explains the absence of any enhancement of the superconducting transition temperature at the QCP. The presence of two components in the nematic fluctuations spectrum is attributed to the dual aspect of electronic degrees of freedom in Hund’s metals, with both itinerant carriers and local moments contributing to the nematic susceptibility.

scholarly journals Avoided ferromagnetic quantum critical point in pressurized La5Co2Ge3

2021 ◽  
Vol 103 (5) ◽  
Author(s):  
Li Xiang ◽  
Elena Gati ◽  
Sergey L. Bud'ko ◽  
Scott M. Saunders ◽  
Paul C. Canfield
Keyword(s):  
Critical Point ◽  
Quantum Critical Point ◽  
Quantum Critical
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