Laser-Induced Ultrafast Magnetic Phenomena

Abstract

Optical manipulation of magnetization with femtosecond laser pulses has opened a new paradigm shift in magnetization and spin dynamics. Since the very first demonstration of femtosecond laser-induced demagnetization in 1996 by Beaurepaire et al., optical manipulation of magnetization has developed into a highly active area of research that has been growing at a breathtaking pace over the last decades. Scientific highlights include the discovery of femtosecond timescale laser-induced demagnetization, all-optical generation of coherent spin waves, photo-induced generation of magnetization, and many others. Undoubtedly, the most appealing is the recent demonstration of all-optical magnetization reversal and opto-magnetic recording with femtosecond laser pulses. All-optical magnetization switching (AOS) is emerging as a novel magnetic recording technology, its potential being fully recognized by the magnetic recording industry, which enlisted the AOS process on its roadmap toward ultrafast and ultrahigh densities magnetic recording beyond 1 Tb/in2. Here we review experimental work, models developed to explain these experiments, and introduce relevant theoretical concepts needed to construct these models. Validity of different involved methods and approximations is critically examined, employing ab initio calculation results where possible. Proposed explanations of ultrafast magnetization dynamics involve different underlying physical mechanisms, the last section of the review provides a discussion of the possible contributions of these mechanisms. We note that the ultrafast magnetism field has become very vast and the present review cannot exhaustively describe all the works related to laser-induced magnetization dynamics.