This thesis presents an experimental study of ordering phenomena in rare-earth nickelate-based heterostructures by means of inelastic Raman light scattering and elastic resonant x-ray scattering (RXS). Further, it demonstrates that the amplitude ratio of magnetic moments at neighboring nickel sites can be accurately determined by RXS in combination with a correlated double cluster model, and controlled experimentally through structural pinning of the oxygen positions in the crystal lattice. The two key outcomes of the thesis are: (a) demonstrating full control over the charge/bond and spin order parameters in specifically designed praseodymium nickelate heterostructures and observation of a novel spin density wave phase in absence of the charge/bond order parameter, which confirms theoretical predictions of a spin density wave phase driven by spatial confinement of the conduction electrons; and (b) assessing the thickness-induced crossover between collinear and non-collinear spin structures in neodymium nickelate slabs, which is correctly predicted by drawing on density functional theory.

In this thesis chemical and epitaxial degrees of freedom are used to manipulate charge and spin ordering phenomena in two families of transition metal oxides, while taking advantage of state-of-the-art resonant x-ray scattering (RXS) methods to characterize their microscopic origin in a comprehensive manner. First, the relationship of charge density wave order to both magnetism and the "pseudogap" phenomenon is systematically examined as a function of charge-carrier doping and isovalent chemical substitution in single crystals of a copper oxide high-temperature superconductor. Then, in copper oxide thin films, an unusual three-dimensionally long-range-ordered charge density wave state is discovered, which persists to much higher temperatures than charge-ordered states in other high-temperature superconductors. By combining crystallographic and spectroscopic measurements, the origin of this phenomenon is traced to the epitaxial relationship with the underlying substrate. This discovery opens new perspectives for the investigation of charge order and its influence on the electronic properties of the cuprates. In a separate set of RXS experiments on superlattices with alternating nickel and dysprosium oxides, several temperature- and magnetic-field-induced magnetic phase transitions are discovered. These observations are explained in a model based on transfer of magnetic order and magneto-crystalline anisotropy between the Ni and Dy subsystems, thus establishing a novel model system for the interplay between transition-metal and rare-earth magnetism.

This PhD thesis reports on investigations of several oxide-based materials using advanced infrared and Raman spectroscopy techniques and in combination with external stimuli such as high magnetic or electric field, sptial confinement in thin film heterostructures and the radiation with UV light. This leads to new results in the fields of superconductivity, electronic polarization states and nanoscale phenomena. Among these, the observation of anomalous polar moments is of great relevance for understanding the electric-field-induced metal-to-insulator transistion; and the demonstration that confocal Raman spectroscopy of backfolded acoustic photons in metal-oxide multilayers can be used as a powerful characterization tool for monitoring their interface properties and layer thickness is an important technical development for the engineering of such functional oxide heterostructures.

Electrochemical energy storage devices are the prime interest of researchers and students. This book provides a comprehensive introduction to nanomaterials and their potential applications specifically for electrochemical devices (rechargeable batteries, supercapacitors and so forth) in a coherent and simple manner. It covers fundamental concepts of nanomaterials, chemical and physical methods of synthesis, properties, characterization methods, and related applications. Features: Introduces the evolution of nanoparticles in electrochemical energy storage devices. Provides the detailed information on step-by-step synthesis of nanoparticles. Discusses different characterization methods (structural, electrical, optical, and thermal). Includes the use of nanoparticles in various electrochemical devices. Aims to bridge the gap between the material synthesis and the real application. This book aims at Senior Undergraduate/Graduate students in Material Chemistry, Electrochemistry and Chemical Engineering, and Energy Storage.

This thesis explores an amazing family of oxide compounds - the nickelates - known for their metal-to-insulator transition and, in the case of LaNiO3, to be a possible building block for designing a synthetic high Tc superconductor. Competition between various fascinating phases makes these materials very sensitive to external parameters and it is thus possible to dramatically tune their properties. This work on ultrathin LaNiO3 and the solid solution Nd1-xLaxNiO3 has important implications for the search for superconductivity in this class of materials.