Mimicking the earth core conditions with ultrafast laser materials interaction

Ultrafast lasers create extreme, non-equilibrium thermodynamic conditions that can transiently reach pressures and temperatures comparable to interior core of the earth. Here we show that femtosecond excitation of amorphous silica-hafnia multilayer dielectrics drives the formation of high-pressure crystalline phases of silica including stishovite, seifertite, and the pyrite-type high density structure, within confined subsurface regions.Using TEM, SAED, and 4D-STEM, we directly map nanoscale phase evolution and identify crystalline motifs embedded inside laser generated blisters.Complementary molecular dynamics simualtions reveal the thermodynamic pathway underlying these transformations, where rapid electronic pressure initiates densification and octahedral coordination, followed by temperature driven crystallization and displacive transitions during ultrafast quenching. The resulting polymorphs reflects a dual-stage pathway inaccessible under equilibrium processing. Our results establish femtosecond laser excitation as a viable route to synthesize and stabilize ultrahigh-density high pressure silica phases under ambient conditions, without a diamond anvil cell, with implications for laser-damage mechanisms, high-energy-density materials, and planetary physics.