%AMandal, P.%AMandal, P.%ASarkar, Tarapada%ASarkar, Tarapada%AGreene, Richard%AGreene, Richard%BJournal Name: Proceedings of the National Academy of Sciences; Journal Volume: 116; Journal Issue: 13; Related Information: CHORUS Timestamp: 2019-12-10 14:48:46 %D2019%IProceedings of the National Academy of Sciences %JJournal Name: Proceedings of the National Academy of Sciences; Journal Volume: 116; Journal Issue: 13; Related Information: CHORUS Timestamp: 2019-12-10 14:48:46 %K %MOSTI ID: 10087945 %PMedium: X %TAnomalous quantum criticality in the electron-doped cuprates %X

In the physics of condensed matter, quantum critical phenomena and unconventional superconductivity are two major themes. In electron-doped cuprates, the low critical field (HC2) allows one to study the putative quantum critical point (QCP) at low temperature and to understand its connection to the long-standing problem of the origin of the high-TCsuperconductivity. Here we present measurements of the low-temperature normal-state thermopower (S) of the electron-doped cuprate superconductor La2−xCexCuO4(LCCO) fromx= 0.11–0.19. We observe quantum criticalS/Tversusln(1/T)behavior over an unexpectedly wide doping rangex= 0.15–0.17 above the QCP (x= 0.14), with a slope that scales monotonically with the superconducting transition temperature (TCwith H = 0). The presence of quantum criticality over a wide doping range provides a window on the criticality. The thermopower behavior also suggests that the critical fluctuations are linked withTC. Above the superconductivity dome, atx= 0.19, a conventional Fermi-liquidSTbehavior is found forT40 K.

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