Amplification of a Seed Magnetic Field (0.1 T) to Mega-Gauss Scale in Femtosecond Ultraintense Laser-Solid Interaction, Unveiling a Magnetic Dynamo*

Generating a powerful and quasistatic magnetic field within the confines of a tabletop laboratory experiment has proven to be a persistent challenge. The creation of magnetized high energy density physics through such experiments presents significant opportunities for exploring several terrestrial as well as astrophysical phenomena, apart from controlling relativistic electron transport, directly relevant to fusion schemes. Here we demonstrate that the modest magnetic field (0.1 tesla) in a common, readily available Neodymium magnet excited by an ultraintense, femtosecond laser pulse generates and amplifies axial quasistatic magnetic field to megagauss levels lasting a few picoseconds. The experimental findings are strongly supported by Particle-in-cell simulations, which validate the observations and unveil a potential dynamo mechanism responsible for the enhancement and amplification of the axial magnetic field. These outcomes are of utmost importance in comprehending the intricacies of relativistic electron transport and magnetized laboratory astrophysics.