Czochralski Growth of YSGAG Crystals: Experimental, Numerical, and Data-Assisted Analysis of Solid–Liquid Interface Shape

Yttrium scandium gallium aluminum garnet (YSGAG) is a promising diamagnetic substrate for yttrium iron garnet thin films, but scalable Czochralski growth requires control of the solid–liquid interface. Here, growth experiments, thermophysical-property measurements, and CGSim simulations are combined to analyze interface-shape control in YSGAG. The Computational Fluid Dynamics (CFD) model was constrained and assessed using experimentally observed interface profiles from early, middle, and late stages of the constant-diameter regime. The resulting model was used to generate a 190-point CFD dataset spanning crystal diameter, rotation rate, growth rate, initial melt charge, and crystallized fraction. A Gaussian-process surrogate, combined with Sobol sensitivity analysis, accumulated local effects, Spearman correlations, and SHAP attribution, was used to identify process correlations controlling interface deflection. Crystallized fraction was the dominant variable, while crystal diameter and rotation rate showed secondary, interaction-dependent effects. The results show that interface flattening in YSGAG should be treated as a coupled, growth-stage-aware control problem rather than as an isolated single-parameter adjustment.