  Reduced dimensionality leads to emergent phenomena in quantum materials and
there is a need for accelerated materials discovery of nanoscale quantum
materials in reduced dimensions. Thermomechanical nanomolding is a rapid
synthesis method that produces high quality single-crystalline quantum
nanowires with controlled dimensions over wafer-scale sizes. Herein, we apply
nanomolding to fabricate nanowires from bulk feedstock of MoP, a triple-point
topological metal with extremely high conductivity that is promising for
low-resistance interconnects. Surprisingly, we obtained single-crystalline
Mo$_{4}$P$_{3}$ nanowires, a metastable phase at room temperature in
atmospheric pressure. We thus demonstrate nanomolding can create metastable
phases inaccessible by other nanomaterial syntheses and can explore a
previously inaccessible synthesis space at high temperatures and pressures.
Furthermore, our results suggest that the current understanding of interfacial
solid diffusion for nanomolding is incomplete, providing opportunities to
explore solid-state diffusion at high-pressure and high-temperature regimes in
confined dimensions.
