Vortex dynamics study on an uniaxially textured YBCO/MgO superconducting film from magnetic measurements

Cornejo H.S.; Domínguez A.B.; Holmes S.N.; Seo J.W.; Aguiar J.A.; Silva V.A.J.; Barnes C.H.W.; De Los Santos Valladares L. · Superconductor Science and Technology (2025) · DOI: 10.1088/1361-6668/adb6d8

Resumen

The vortex dynamics of an undoped uniaxially textured YBa2Cu3O7−δ (YBCO) superconducting film grown onto a MgO (100) substrate was inspected by applying the vortex glass and collective-pinning models. The texture and structural characterization studied by X-ray diffraction revealed a uniaxially (00 l) YBCO layer, which coexists with minor Y2BaCuO5 and CuO phases. The temperature dependence of the magnetization in the superconducting state revealed a critical temperature T C = 88 K. By measuring the hysteresis loops ( M ( H ) ) at 10-70 K, the critical fields H C 1 , H C 2 , H P and H irr were estimated and a vortex matter diagram was sketched. By using the Bean model, the critical current density values J C ( T , H ) were obtained and the typical peak effect is observed. The vortex dynamics mechanism is discussed taking into account four vortex feature regimes in the double-logarithmical J C ( H ) curves. The vortex pinning mechanism is discussed by obtaining the pining force, F P , its normalization, f ( h ) , and magnetic relaxation M ( t ) measurements taken in field cooling mode at 10-60 K. The glassy exponent μ and the characteristic energy U ( J , T ) in the vortex glass model were estimated following the Maley method. The collective-pinning model is used to discuss the possible vortex regimes mechanism (individual flux lines, small bundles and large bundles of pinned flux). Eventually, the E ( J ) curves, expressed from the swept field and creep measurements, show a power-law behaviour, in agreement with the vortex matter.

Instituciones: Universidad Nacional Mayor de San Marcos