Faculté des sciences

Evidence for two separate energy gaps in underdoped high-temperature cuprate superconductors from broadband infrared ellipsometry

Yu, Li ; Munzar, D. ; Boris, A. V. ; Yordanov, P. ; Chaloupka, J. ; Wolf, Th. ; Lin, C. T. ; Keimer, B. ; Bernhard, Christian

In: Physical Review Letters, 2008, vol. 100, p. 177004

We present broadband infrared ellipsometry measurements of the c-axis conductivity of underdoped RBa₂Cu₃O₇₋δ (R=Y, Nd, and La) single crystals. Our data show that separate energy scales are underlying the redistributions of spectral weight due to the normal state pseudogap and the superconducting gap. Furthermore, they provide evidence that these gaps do not... Plus

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    Summary
    We present broadband infrared ellipsometry measurements of the c-axis conductivity of underdoped RBa₂Cu₃O₇₋δ (R=Y, Nd, and La) single crystals. Our data show that separate energy scales are underlying the redistributions of spectral weight due to the normal state pseudogap and the superconducting gap. Furthermore, they provide evidence that these gaps do not share the same electronic states and do not merge on the overdoped side. Accordingly, our data are suggestive of a two gap scenario with a pseudogap that is likely extrinsic with respect to superconductivity.