Ultrafast demagnetization in ferromagnetic materials: Origins and progress

TL;DR

This review discusses the experimental methods, models, and physical origins of ultrafast demagnetization in ferromagnetic materials, highlighting recent advances, challenges, and emerging research directions in ultrafast spin dynamics and spintronics.

Contribution

It systematically reviews the models and physical mechanisms of ultrafast demagnetization, and discusses recent developments in attosecond laser techniques and antiferromagnetic materials for spintronics.

Findings

Seven models of ultrafast demagnetization are presented.

Four physical origins of ultrafast demagnetization are discussed.

Emerging applications in attosecond laser techniques and antiferromagnets are highlighted.

Abstract

Since the discovery of ultrafast demagnetization in Ni thin films in 1996, laser-induced ultrafast spin dynamics have become a prominent research topic in the field of magnetism and spintronics. This development offers new possibilities for the advancement of spintronics and magnetic storage technology. The subject has drawn a substantial number of researchers, leading to a series of research endeavors. Various models have been proposed to elucidate the physical processes underlying laser-induced ultrafast spin dynamics in ferromagnetic materials. However, the potential origins of these processes across different material systems and the true contributions of these different origins remain challenging in the realm of ultrafast spin dynamics. This predicament also hinders the development of spintronic terahertz emitters. In this review, we initially introduce the different experimental methods used in laser-induced ultrafast spin dynamics. We then systematically explore the magnetization precession process and present seven models of ultrafast demagnetization in ferromagnetic materials. Subsequently, we discuss the physical processes and research status of four ultrafast demagnetization origins (including spin-flipping, spin transport, non-thermal electronic distribution, and laser-induced lattice strain). Since attosecond laser technique and antiferromagnetic materials exhibit promising applications in ultrahigh-frequency spintronics, we acknowledge the emerging studies used by attosecond pules and studies on ultrafast spin dynamics in antiferromagnets, noting the significant challenges that need to be addressed in these burgeoning field.