  The insulator-metal transition in Mott insulators, known as the Mott
transition, is usually accompanied with various novel quantum phenomena, such
as unconventional superconductivity, non-Fermi liquid behavior and colossal
magnetoresistance. Here, based on high-pressure electrical transport and XRD
measurements, and first-principles calculations, we find that a unique
pressure-induced Mott transition from an antiferromagnetic Mott insulator to a
ferromagnetic Weyl metal in the iron oxychalcogenide La2O3Fe2Se2 occurs around
37 GPa without structural phase transition. Our theoretical calculations reveal
that such an insulator-metal transition is mainly due to the enlarged bandwidth
and diminishing of electron correlation at high pressure, fitting well with the
experimental data. Moreover, the high-pressure ferromagnetic Weyl metallic
phase possesses attractive electronic band structures with six pairs of Weyl
points close to the Fermi level, and its topological property can be easily
manipulated by the magnetic field. The emergence of Weyl fermions in
La2O3Fe2Se2 at high pressure may bridge the gap between nontrivial band
topology and Mott insulating states. Our findings not only realize
ferromagnetic Weyl fermions associated with the Mott transition, but also
suggest pressure as an effective controlling parameter to tune the emergent
phenomena in correlated electron systems.
