Even though a considerable effort has been spent in investigating the transport properties of electron doped cuprates, different theoretical interpretations of the experimental data have been proposed, some of them in apparent contradiction with each other, ranging from Fermi liquid behavior to spin-fluctuation scattering mechanisms. To further complicate the general properties of the normal-state physics of electron doped cuprates, the disappearance of any superconductivity phase has been found for a very low normal-state sheet resistance values. Indeed, such a crossover has been measured for a kFl value of about 13, sizable higher than the critical values of 4 and 1 reported for both high- and low-temperature superconductors, respectively. Such a puzzling scenario has thus prevented, up to now, the full understanding of the low temperature upturn of resistivity and the crossover from the metallic/superconducting phase to a fully insulating ones. With the aim of revealing the true nature of normal-state resistivity in electron-doped cuprates, the transport properties of a wide series of infinite layer Sr1-xLaxCuO2±d thin films have been detailed investigated. Infinite-layer cuprate structures, as discussed here, offer unique opportunities to define the proper regime of the transport properties being removed the ambiguity in the definition of the effective thickness of the conducting layer. Our starting point has been the underdoped regime, where localization effects are clearly demonstrated by the upturn of the resistivity, proved to be determined by quantum interference effects (QIEs). Once established, QIEs have been traced back also in optimal- and over-doped samples, even though in these last samples a metal-to-insulator transition does not occur. Evidence arises that QIEs co-exist with a pure metallic phase and severely affects the normal-state transport properties in proximity of superconducting transition. Such a phase separation scenario has therefore allowed to reveal the true nature of the metallic phase of electron doped cuprates, which is found to be unambiguously dominated by spin-fluctuation phenomena at any temperatures. Our results provide ultimate demonstration of a unified and universal electron/hole doped phase diagram.

Unified and universal electron/hole doped normal-state phase diagram ruled by spin-fluctuation phenomena

GALDI, ALICE;SACCO, CHIARA;MARITATO, Luigi
2014

Abstract

Even though a considerable effort has been spent in investigating the transport properties of electron doped cuprates, different theoretical interpretations of the experimental data have been proposed, some of them in apparent contradiction with each other, ranging from Fermi liquid behavior to spin-fluctuation scattering mechanisms. To further complicate the general properties of the normal-state physics of electron doped cuprates, the disappearance of any superconductivity phase has been found for a very low normal-state sheet resistance values. Indeed, such a crossover has been measured for a kFl value of about 13, sizable higher than the critical values of 4 and 1 reported for both high- and low-temperature superconductors, respectively. Such a puzzling scenario has thus prevented, up to now, the full understanding of the low temperature upturn of resistivity and the crossover from the metallic/superconducting phase to a fully insulating ones. With the aim of revealing the true nature of normal-state resistivity in electron-doped cuprates, the transport properties of a wide series of infinite layer Sr1-xLaxCuO2±d thin films have been detailed investigated. Infinite-layer cuprate structures, as discussed here, offer unique opportunities to define the proper regime of the transport properties being removed the ambiguity in the definition of the effective thickness of the conducting layer. Our starting point has been the underdoped regime, where localization effects are clearly demonstrated by the upturn of the resistivity, proved to be determined by quantum interference effects (QIEs). Once established, QIEs have been traced back also in optimal- and over-doped samples, even though in these last samples a metal-to-insulator transition does not occur. Evidence arises that QIEs co-exist with a pure metallic phase and severely affects the normal-state transport properties in proximity of superconducting transition. Such a phase separation scenario has therefore allowed to reveal the true nature of the metallic phase of electron doped cuprates, which is found to be unambiguously dominated by spin-fluctuation phenomena at any temperatures. Our results provide ultimate demonstration of a unified and universal electron/hole doped phase diagram.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11386/4565270
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