Abstract
Tunneling effects in YbBa2Cu3O7−x (YbBCO) and YbBa2Cu3O7−x (YBCO) single crystals have been investigated using an improved technique of break junction preparation. A two-gap structure with BCS-like density of states has been observed. The value of the “large” gap is in the range of 24–28 meV for YBCO (T c =85–90 K) and 29–30 meV for YbBCO (T c =87–90 K). A variation of the value of the “small” gap between 0.5 and 11 meV has been detected, even for the same crystal. As a possible explanation, two-band superconductivity, surface properties, or strong gap anisotropy will be discussed.
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Aminov, B.A., Hein, M.A., Müller, G. et al. Two-gap structure in Yb(Y)Ba2Cu3O7−x single crystals. J Supercond 7, 361–365 (1994). https://doi.org/10.1007/BF00724569
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DOI: https://doi.org/10.1007/BF00724569