title: Fundamental mechanism for all-optical helicity-dependent switching of magnetization.
abstract: Switching magnetizations with femtosecond circularly polarized lasers may have revolutionary impacts on magnetic data storage and relevant applications. Achievements in ferrimagnetic and ferromagnetic materials of various structures strongly imply a general phenomenon of fundamental atom-laser interaction. Rotating an atom's wave function with the rotating electric field of a circularly polarized laser, I show the quantum mechanics for the atom is equivalent to that in a static electric field of the same magnitude and a tremendous static magnetic field which interacts with the atom in somewhat different ways. When some conditions are satisfied, transitions of atoms in these two crossed effective fields lead to a highly nonequilibrium state with orbital magnetic moments inclining to the effective magnetic field. The switching finally completes after the pulse duration via relaxation.
authors.affiliation: Department of Physics, Jinan University, Guangzhou 510632, P. R. China.
authors.forename: Xiang-Jun
authors.initials: XJ
authors.lastname: Chen