Anomalous quantum criticality in the electron-doped cuprates

Abstract

In the physics of condensed matter, quantum critical phenomena and unconventional superconductivity are two major themes. In electron doped cuprates, the low upper critical field allows one to study the putative QCP at low temperature and to understand its connection to the long standing problem of the origin of the high Tc superconductivity. Here we present measurements of the low temperature normal state thermopower (S) of the electron-doped cuprate superconductor La2-xCexCuO4 (LCCO) from x=0.11 to 0.19. We observe quantum critical S divided by T versus ln(1/T) behavior over an unexpectedly wide doping range x = 0.15 - 0.17 above the putative QCP (x=0.14) with a slope that scales monotonically with the superconducting transition temperature. The presence of quantum criticality over a wide doping range provides a new window on the criticality. The thermopower behavior also suggests that the critical fluctuations are linked with Tc. Above the superconductivity dome, at x=0.19, a conventional Fermi liquid S proportional to T behavior is found for T less than equal to 40 K.

arXiv comment16 pages, 5 figures

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• The Strange Metal State of the Electron-Doped Cuprates
• Ferromagnetic order beyond the superconducting dome in a cuprate superconductor
• The strange metal Hall effect connects quantum criticality and superconductivity in an iron-based superconductor
• Thermoelectric signature of quantum critical phase in a doped spin liquid candidate
• Disorder effects on hot spots in electron-doped cuprates
• In-situ electrical and thermal transport properties of FeySe1-xTex films with ionic liquid gating
• The Strange Metal State of the high-Tc Cuprates
• Magnetic field-tuned quantum criticality in optimally electron-doped cuprate thin films
• Non-Fermi liquid transport and strong mass enhancement near the nematic quantum critical point in FeSe${}_x$Te${}_{1-x}$ thin films
• Valence Transition Theory of the Pressure-Induced Dimensionality Crossover in Superconducting Sr${}_{14-x}$Ca${}_x$Cu${}_{24}$O${}_{41}$
• Superlinear Hall angle and carrier mobility from non-Boltzmann magnetotransport in the spatially disordered Yukawa-Sachdev-Ye-Kitaev model on a square lattice
• Inhomogeneous reduction-annealing effects on the electron-doped cuprate superconductor revealed by micro-focused angle-resolved photoemission spectroscopy