ybco films

ca cu

ba cu

bi pb

superconducting properties

critical current density

flux pinning

penetration depth

yba cu

high tc

Scientific Reports

The functional properties of cuprates are strongly determined by the doping state and carrier density. We present an oxygen doping study of YBa 2 Cu 3 O 7-δ (YBCO) thin films from underdoped to overdoped state, correlating the measured charge carrier density, $${n}_{\mathrm{H}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>n</mml:mi> <mml:mi>H</mml:mi> </mml:msub> </mml:math> , the hole doping, p , and the critical current density, $${J}_{c}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>J</mml:mi> <mml:mi>c</mml:mi> </mml:msub> </mml:math> . Our results show experimental demonstration of strong increase of $${J}_{c}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>J</mml:mi> <mml:mi>c</mml:mi> </mml:msub> </mml:math> with $${n}_{\mathrm{H}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>n</mml:mi> <mml:mi>H</mml:mi> </mml:msub> </mml:math> , up to Quantum Critical Point (QCP), due to an increase of the superconducting condensation energy. The ultra-high $${J}_{c}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>J</mml:mi> <mml:mi>c</mml:mi> </mml:msub> </mml:math> achieved, 90 MA cm −2 at 5 K corresponds to about a fifth of the depairing current, i.e. a value among the highest ever reported in YBCO films. The overdoped regime is confirmed by a sudden increase of $${n}_{\mathrm{H}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>n</mml:mi> <mml:mi>H</mml:mi> </mml:msub> </mml:math> , associated to the reconstruction of the Fermi-surface at the QCP. Overdoping YBCO opens a promising route to extend the current carrying capabilities of rare-earth barium copper oxide (REBCO) coated conductors for applications.

Ultra-high critical current densities of superconducting YBa2Cu3O7-δ thin films in the overdoped state