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About this book

This book provides a comprehensive overview of the latest developments in the field of spin dynamics and magnetic damping. It discusses the various ways to tune damping, specifically, dynamic and static control in a ferromagnetic layer/heavy metal layer. In addition, it addresses all optical detection techniques for the investigation of modulation of damping, for example, the time-resolved magneto-optical Kerr effect technique.

Table of Contents


Chapter 1. Introduction

Magnetism has been a subject of intense research for more than a century as it has played a pivotal role for the benefit of mankind. Starting from old-age magnetic compass used for navigation, magnetism has numerous applications in modern and future data storage technology.
Anjan Barman, Jaivardhan Sinha

Chapter 2. Spin Dynamics

As briefly mentioned in the introduction of Chap. 1, the spin dynamics has been a topic of intense research to address several intriguing fundamental physics issues. In this chapter, we describe various time scales involved with spin dynamics in detail.
Anjan Barman, Jaivardhan Sinha

Chapter 3. Magnetic Damping

In this chapter, we focus on various aspects of magnetic damping. As described in the previous chapters, in a ferromagnetic system the spin dynamics is described by using Landau–Lifshitz–Gilbert (LLG) equation in which a phenomenological parameter α defines a magnetization relaxation.
Anjan Barman, Jaivardhan Sinha

Chapter 4. Experimental Techniques to Investigate Spin Dynamics

As discussed in the Chap. 2, the time scale for magnetization dynamics varies from microseconds (μs) to femtoseconds (fs) which depends on the mechanism involved.
Anjan Barman, Jaivardhan Sinha

Chapter 5. Factors Affecting Spin Dynamics

As discussed in previous chapters, the precessional magnetization dynamics is described by Landau–Lifshitz–Gilbert equation. It may be noticed from the LLG equation that four important material parameters, namely, Landé g-factor, saturation magnetization, magnetic anisotropy, and Gilbert damping parameters directly govern the precessional dynamics. Ultrafast demagnetization and relaxation phenomena are also influenced by material parameters and sample conditions. To understand deeply, various factors related to material aspects of the specimen which affect the dynamics, numerous interesting theoretical and experimental studies have been performed.
Anjan Barman, Jaivardhan Sinha

Chapter 6. Electrical and Optical Control of Spin Dynamics

As discussed in previous chapters, in early days, the magnetization dynamics was primarily investigated using high-frequency techniques based on electrical excitation and detection.
Anjan Barman, Jaivardhan Sinha

Chapter 7. Tunable Magnetic Damping in Ferromagnetic/Non-magnetic Bilayer Films

With the advancement in the methods for thin film deposition, tailoring of magnetic properties of thin ferromagnetic layer by using a neighboring layer has gained attention of researchers. From the perspective of fundamental understanding, the role of interface in different bilayer and multilayer systems has been an intense area of investigation. Utilizing the additional tunable properties originating from the interface has been foreseen as a route to improve the performance of numerous devices in application. In this chapter, the important aspect of magnetic damping in ferromagnetic/non-magnetic (FM/NM) bilayer films with primary focus on the recent experimental results is presented. Before describing various cases, we discuss two important mechanisms involved in FM/NM bilayer system, namely spin pumping and interfacial d-d hybridization.
Anjan Barman, Jaivardhan Sinha

Chapter 8. Summary and Future Direction

Spin dynamics in ferromagnetic thin films, nanostructures, and heterostructures have drawn significant attention due to the application potential in various magnetic devices and the fundamental physics involved in it. In this book, we have described, in reasonable detail, the spin dynamics in various systems starting from its historical evolution. We reviewed experimental and theoretical results related to the ultrafast demagnetization, relaxation, magnetization precession, and magnetic damping in ferromagnetic metallic thin films, bilayers, and nanostructures with a particular focus on these systems when excited by femtosecond (fs) optical pulses. In order to better understand the experimental techniques, theoretical backgrounds of magnetization dynamics are discussed.
Anjan Barman, Jaivardhan Sinha
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