  We present an atomistic study of heterogeneous nucleation in Ni employing
transition path sampling, which reveals a template precursor-mediated mechanism
of crystallization. Most notably, we find that the ability of tiny templates to
modify the structural features of the liquid and promote the formation of
precursor regions with enhanced bond-orientational order is key to determine
their nucleation efficiency and the polymorphs that crystallize. Our results
reveal an intrinsic link between liquid heterogeneity and the nucleating
ability of templates, which significantly advances our understanding towards
the control of nucleation efficiency and polymorph selection.
