Rare-earth intermetallics, also known as lanthanide elements, play an important role in the study of magnetic materials and the development of semi- and super-conducting materials. This handbook provides an up-to-date compilation of crystallographic, physical, and magnetic data on rare-earth intermetallic compounds. Over 20 different structure types are described in detail with an emphasis on how crystal structure can affect magnetic properties. Theoretical models for magnetic interactions are described as well as the impact of crystal electric fields on transport properties, magneto crystalline anistropy and hyperfine interactions. This book provides materials scientists, engineers and physicists with all the critical information needed to use rare-earth intermetallics effectively in the development of new materials.

The electronic structures of EuNi2Ge2 and GdNi2Ge2 have been investigated using photoemission spectroscopy. The majority of the photoemission intensity near E[subscript F] was due to the mostly Ni 3d states in both materials. CIS spectra were recorded at selected initial-state binding energies (BEs) across the excitation energy range of the Ni 3p threshold in EuNi2Ge2. It is apparent that there is strong Ni d character throughout the valence band from CIS spectra. Resonance measurements of the Eu 4d[Reaction goes right]4f excitations in EuNi2Ge2 reveal that Eu 4f states are localized around 2 eV below E[subscript F]. It is observed that Gd 4f peak in GdNi2Ge2 is more tightly bound by 6.4 eV than in Eu 4f peak in EuNi2Ge2. We have seen a resonant enhancement of the Ni 3d satellite at about 7.4 eV BE, indicating Ni 3d character around the Fermi edge in EuNi2Ge2. The Ni 3d partial spectral weights (PSW) from the Ni 3p[Reaction goes right]3d RPES measurements show that they are very close to the calculated Ni 3d density of states for both materials. We have measured Constant-Final-State (CFS) and Constant-Initial-State (CIS) spectra in an attempt to check the valence of the Eu ion in EuNi2Ge2, and it is verified as 2+. The measured CFS spectra of GdNi2Ge2 was almost the same as those of EuNi2Ge2 and Gd metal, indicating that Gd ions in GdNi2Ge2 are trivalent with the same 4f7 configuration as the Eu ion in EuNi2Ge2. We present experimental energy bands mapped from normal-emission photoelectron spectra of EuNi2Ge2 and GdNi2Ge2 (001) surfaces using synchrotron radiation with increasing photon energies from 14 eV to 54 eV (to 44 eV in the case of GdNi2Ge2). Four and three major photoemission features disperse along the normal [001] Brillouin zone (BZ) direction direction in EuNi2Ge2 and GdNi2Ge2, respectively, in good agreement with the band calculations. We studied quantitatively the effects of band filling on the electronic structures by observing a rigid-band shift of E[subscript F] corresponding simply to an increase of one conduction electron upon going from EuNi2Ge2 to GdNi2Ge2. Segments of the Fermi surfaces (FSs) were mapped by ARPES in the [Gamma]XPZ plane of the Brillouin zones (BZs) for both EuNi2Ge2 and GdNi2Ge2, which are in good agreement with band calculations. We studied how the FS is changed in the [Gamma]XPZ planes of the BZ when one electron is added to EuNi2Ge2, corresponding to GdNi2Ge2, based on the rigid-band approximation. In conclusion, these compounds which give the same Hund's rule ground state (8S--[subscript /]2) were one of suitable systems for the study of effects of band filling on electric structures based on a rigid-band model as a first-order approximation.

This volume covers various physical aspects of a wide range of rare-earth materials. Magnetic phenomena dominate the contents of the first four chapters which deal with thin films and layered structures, and intermetallic and nonmetallic compounds. The remaining two chapters deal with coherent emission and electronic structure calculations of lanthanide molecules.The first chapter covers the state-of-the-art of the synthesis and properties of thin films of the rare-earth metals and layered superstructures of two rare-earth metals. The following chapter is a review of rare-earth-transition metal nanoscale multilayers and describes the recent advances in our understanding of magnetic structure, interfacial magnetism, and origin of perpendicular magnetic anisotropy of lanthanide-transition-metal nanoscale multilayers. The next chapter deals with one of the important series of rare-earth intermetallic compounds, those which possess the ThNm 12 -type structure. The authors of the following chapter review the specific magnetic and magnetoelastic properties of certain crystals, which are determined by the localized electronic magnetic moments of the lanthanide ions in the crystal lattice and their interactions with each other and surrounding ions. The chapter on coherent emission differs from other reviews on the subject in that it concentrates on the broader issues. Here the emphasis is on superradiance, superfluorescence, amplification of spontaneous emission by other stimulated emision than the laser effect and coherent spontaneous emission. The final chapter describes the progress that has been made in electronic structure calculations of lanthanide-containing molecules, especially in the last 10 years.

This volume contains most of the contributions presented at the NATO Advanced Research Workshop on Rare Earth Transition Metal Borocarbides (Nitrides): Superconducting, Magnetic and Normal State Properties, held in Dresden, Germany at 13 - 18 June 2000. The Workshop was chaired by K. -H. MUller and V. N. Narozhnyi. This was the first meeting specially focused on the quaternary rare-earth transition-metal borocarbides and nitrides - a new class of magnetic superconductors discovered in 1994. The motivation for organizing this workshop was to bring together scientists (both experimentalists and theoreticians), actively working in this field in different countries, using different methods, to exchange their points of view on the properties ofthese materials and to recognize the directions for future research. Totally 48 participants from 17 countries ofEurope, the United States, BraZil, India, Israel and Japan took part in this meeting. In addition about 15 observers (mainly from Germany) attended. The scientific Programme of the Workshop was composed of 7 sections. The section Introduction and Overview was followed by the Electronic Structure and Properties and Phonon Spectra; Magnetic Properties and CEF Effects; Interplay between Superconductivity and Magnetism; Vortex Lattice; Thin Films; Nature of the Superconducting State in Borocarbides sections. Totally 50 presentations were given (45 ofthem in oral form). Considerable attention was devoted to the characterization of the particular place of borocarbides amongst the other magnetic and superconducting systems and, especially, magnetic superconductors.

This book on the magnetic properties of 3d-transition metal compounds focuses on 3d-metal pnictides. It couples experimental data with phenomenological discussions and explores how certain behaviors can be explained based on an itinerant electron picture.

The purpose of this thesis is to explore novel rare-earth, transition metal compounds and to investigate their structure and bonding and how these influence their properties. We have focused on the synthesis, characterization and electronic structure investigations, as well as physical properties of ternary rare-earth Fe-rich intermetallics, e.g., LaFe[subscript 13-x]Si[subscript x], and RE[subscript 2-x]Fe4Si[subscript 14-y], etc. The LaFe[subscript 13-x]Si[subscript x], (1.0 [equal to or less than] x [equal to or less than] 5.0) compounds with structures related to the cubic NaZn13−type are an important series of compounds to study for possible efficient magnetic refrigeration. A systematic structural study of the compositional variation in LaFe[subscript 13-x]Si[subscript x], exhibits a structural transformation from the cubic NaZn13−structure type to a tetragonal derivative due to preferential ordering of Fe and Si atoms. Temperature-dependent single crystal X-ray diffraction at various temperatures and electronic structure calculations (both Extended Hückel and TB-LMTO) was performed on the cubic phases to examine the origin of the large magnetic entropy change. The giant magnetocaloric effect of cubic LaFe[subscript 13-x]Si[subscript x] alloys results from coupling between magnetic ordering and structural transformation. In light of the potential superstructures that could be observed for RE[subscript 2-x]Fe4Si[subscript 14-y] as well as possible modifications of semiconducting [Beta]-FeSi2, we report herein a thorough examination of the chemical composition and structure of RE[subscript 2-x]Fe4Si[subscript 14-y] (RE = Y, Gd-Lu) using a combination of electron microscopy and X-ray diffraction, and demonstrate a new superstructure for this class of compound. The structures are built up of rare-earth silicide planes with approximate compositions "RE1.2Si1.9" alternating with [Beta]-FeSi2-derived (hkl)-type slabs. Investigation by transition electron microscopy (TEM) reveals a superstructure in the crystallographic ab-plane. Fe Mössbauer spectra confirm two different iron environments in superstructure. Magnetic susceptibilities suggest weak magnetic coupling between rare-earth elements, and resistance measurements indicate poor metallic behavior with a large residual resistivity at low temperatures, which is consistent with disorder. Electronic structure calculations on model structures identify a pseudogap in the densities of states for specific valence electron counts that helps to provide a useful electron counting scheme for this class of rare-earth/transition metal/main group compound.