Effect of laser energy density on microstructure and critical current of YGBCO and HGBCO films fabricated by PLD

Abstract

Y_0.5Gd_0.5Ba₂Cu₃O_7-σ (YGBCO) and Ho_0.5Gd_0.5Ba₂Cu₃O_7-σ (HGBCO) targets with similar densities were prepared by solid-phase reaction. Pulsed laser deposition (PLD) technology was used to fabricate superconducting films with these targets. During the experiments in this paper, we varied the laser energy by adjusting the optical lens. The structure and texture of RE_0.5Gd_0.5Ba₂Cu₃O_7-σ (REGBCO, where RE = Y, Ho) thin films were analyzed by X-ray diffraction (XRD). The surface morphology was observed by atomic force microscopy (AFM) and scanning electron microscopy (SEM), and the superconducting critical current was measured at 77 K using the standard four-probe method. The laser energy density and different doping elements can affect the properties of REGBCO films. This may be related to the ejection process of target particles and the size of rare earth atoms. Additionally, we prepared a 510-meter long second-generation high-temperature superconducting tape with the optimized parameters. The critical current of the tape is 350 A, and the current density is 3.9 × 10⁶ A/cm².