REBCO production remains constrained by high costs and increasing demand. The high-throughput growth technique Transient Liquid Assisted Growth (TLAG) [1-3] addresses both challenges, as it enables lower-cost production and achieves ultrahigh growth rates while maintaining high critical current densities [4]. TLAG is a liquid-solid mediated process, where epitaxial REBCO crystallization occurs over a wide range of oxygen partial pressures PO2 and temperatures. The growth rate is measured by in-situ resistivity measurements, revealing a clear correlation between higher growth rates and increased PO2 and temperature, with values ranging from 10 to 5000 nm/s for RE = Y, Er. This work investigates the impact of growth rate on nucleation, crystal growth, defect microstructure, and vortex pinning in TLAG films. Nucleation and growth mechanisms are studied by correlating the in-situ resistivity measurements with in-situ XRD and XAS experiments at ALBA Synchrotron. Magnetic granularity studies [5] and TEM analysis show that higher growth rates produce smaller grain sizes, higher critical currents, and a cleaner microstructure with less secondary phases and porosity. Transport measurements reveal enhanced pinning at high magnetic fields and low temperatures for samples grown at higher PO2, with the complete pinning landscape to be presented at the conference.

[1] L. Soler et al, Nat Commun (2020)

[2] S. Rasi et al, J. Phys. Chem. C (2020)

[3] L. Saltarelli et al, Advanced Materials (2025)

[4] T. Puig et al, Nat. Rev. Phys. (2023)

[5] A. Palau et al, Phys. Rev. B (2007)