Ultrafast optical manipulation of magnetic order in ferromagnetic materials

Abstract

The interaction between ultrafast lasers and magnetic materials is an appealing topic. It not only involves interesting fundamental questions that remain inconclusive and hence need further investigation, but also has the potential to revolutionize data storage technologies because such an opto-magnetic interaction provides an ultrafast and energy-efficient means to control magnetization. Fruitful progress has been made in this area over the past quarter century. In this paper, we review the state-of-the-art experimental and theoretical studies on magnetization dynamics and switching in ferromagnetic materials that are induced by ultrafast lasers. We start by describing the physical mechanisms of ultrafast demagnetization based on different experimental observations and theoretical methods. Both the spin-flip scattering theory and the superdiffusive spin transport model will be discussed in detail. Then, we will discuss laser-induced torques and resultant magnetization dynamics in ferromagnetic materials. Recent developments of all-optical switching (AOS) of ferromagnetic materials towards ultrafast magnetic storage and memory will also be reviewed, followed by the perspectives on the challenges and future directions in this emerging area.

Ultrafast signatures of magnetic inhomogeneity in Pd1−xFex (x ≤ 0.08) epitaxial thin films

“…It does not demand any process related to the paramagnetic fraction, and therefore we denote it as "on-site demagnetization". Indeed, such an ultrafast photoinduced demagnetization is a characteristic feature of the 3d metal ferromagnets that has been a matter of intense discussion in past decades [38][39][40][41][42][43]. An additional demagnetization component with a characteristic time of ≈10 ps requires the presence of a paramagnetic fraction in the material.…”

Ultrafast manipulation of magnetic anisotropy in a uniaxial intermetallic heterostructure TbCo2/FeCo

“…Moreover, advances in ultrafast control of magnetic media with femtosecond laser pulses has begun a new era of opto-magnetism, allowing the development of new devices that operate at high frequency and low power consumption, which cannot be achieved with other techniques. Optical spin manipulation is most often implemented through ultrafast demagnetization [10][11][12][13]. At the same time, femtosecond radiation has a wide range of mechanisms for affecting the spin system.…”

Selector-less Ferroelectric Tunnel Junctions by Stress Engineering and an Imprinting Effect for High-Density Cross-Point Synapse Arrays

“…Hafnia-based ferroelectric materials with electrically switchable polarization have been developed in a wide range of emerging technologies such as nonvolatile memory, − low-power logic transistors, − pyroelectric sensors, − and brain-inspired devices. − Particularly, two-terminal hafnia-based ferroelectric tunnel junctions (FTJs) are considered promising resistive switching memories for artificial synaptic devices in neuromorphic systems. − In FTJs, a nanometer-scale ferroelectric thin film is employed as a tunneling barrier, and the effective barrier height and width can be increased or decreased by changing the direction of polarization, resulting in a high- or low-resistance state. This tunneling conductance, or tunneling electroresistance (TER), can be gradually switched by the partial domain switching of polycrystalline ferroelectrics. , Hafnia-based FTJs have the advantages of simple fabrication, low-power operation, fast switching, and nondestructive readout.…”