Momentum absorption and magnetic field generation by obliquely incident light

The partial reflection of an electromagnetic (EM) wave from a medium leads to absorption of momentum in the direction perpendicular to the surface (the standard radiation pressure) and, for oblique incidence on a partially reflecting medium, also in the parallel direction. This latter component drives a transverse current and a slowly growing, quasi-static magnetic field in the evanescence “skin” layer. Through a simple model we illustrate how EM momentum is transfered to ions and estimate the value of the magnetic field which may be of the order of the driving EM wave field, i.e. up to several hundreds of megagauss for high-intensity laser-solid interactions.