3D-XY critical fluctuations of the thermal expansivity in detwinned YBa2Cu3O7-δ single crystals near optimal doping
نویسندگان
چکیده
The strong coupling of superconductivity to the orthorhombic distortion in YBa2Cu3O7-δ makes possible an analysis of the superconducting fluctuations without the necessity of subtracting any background. The present high-resolution capacitance dilatometry data unambiguously demonstrate the existence of critical, instead of Gaussian, fluctuations over a wide temperature region (± 10 K) around Tc. The values of the amplitude ratio A A + − = − / . . 0 9 11 and the leading scaling exponent | | . α ≤ 0 018 , determined via a leastsquares fit of the data, are consistent with the 3D-XY universality class. Small deviations from pure 3D-XY behavior are discussed.
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