Modeling Magnetic Anisotropy in Single Chain Magnets

Abstract

This thesis embodies work on modeling magnetic anisotropy in molecular magnets. newlineUnderstanding the factors that govern the magnitude of anisotropy in these materials is newlinecrucial for tailoring molecules that can be used in magnetic devices. Here, we explore newlinethe dependence of magnetic anisotropy on factors such as local anisotropy, exchange newlineanisotropy, and magnetic dipolar interactions on both static and dynamic properties. newlineThe contents of the chapters in the thesis are summarized below. newlineIn chapter 1, we provide a brief overview of magnetism and the properties of magnetic newlinematerials. This is followed by an introduction to molecular magnetism and the devel- newlineopment of Single Molecule Magnets (SMMs) and Single Chain Magnets (SCMs). In newlinethe last section of this chapter, we discuss the Magnetocaloric effect (MCE). Molecular newlinemagnets such as SMMs and SCMs have been able to provide an alternative route to the newlinelow-temperature MCE materials. newlineExchange mechanism provides a good basis for the relevant effects in real magnetic newlinematerials. In chapter 2, we discuss direct and kinetic exchange for simple system and newlinethe extension of kinetic exchange ideas to superexchange mechanism. We provide a newlinesimple example of Cu2+ - O2and#8722; -Cu2+ structure and discuss ferromagnetic and antifer- newlineromagnetic exchange in detail. Then we introduce the electronic model Hamiltonians newlinelike Hückel, Hubbard and Pariser-Parr-Popple (PPP) models and discuss their relation newlineto spin Hamiltonians. This is followed by an introduction to Dzyalashinskii-Moria newline(DM) exchange interactions. We also discuss molecular anisotropy parameters and newlinespin-dipolar interaction for spin clusters. newline