Self-Reconstruction of Order Parameter in Spin-Triplet Superconductor UTe_{2}

We investigate the effect of easy-axis metamagnetic crossover on superconductivity in UTe_{2} along the a axis through measurements of ac susceptibility, magnetization, and the magnetocaloric effect. In ultraclean single crystals, we identify a field-induced phase transition within the superconducting state at 5.6 T, driven by metamagnetism. This transition leads to a high-field superconducting state, significantly increasing the upper critical field to 12 T. A sudden increase in entropy at the transition suggests a self-reconstruction of the order parameter, enabling multicomponent superconducting states to adapt to external perturbations.