The structural, magnetic, electronic and optical properties of Terbium-based binaries (TbX) (X = N, O, S and Se) in two cubic structures NaCl and CsCl have been investigated. This study is carried out by Full-Potential linearized Muffin-Tin orbitals (FP-LMTO) method in the framework of the functional theory of density (DFT) implemented in the lmtart code. The presence of f-state electrons in these induced high-correlation materials led us to study these systems using local density approximation (LDA) for the paramagnetic state and spin local density approximation (LSDA) for the ferromagnetic state within two cubic structures. We have demonstrated that these binaries are stable in the ferromagnetic state in the cubic phase of NaCl, which allows us to deduce the magnetic moments of these components. From the electronic band structures and density states, we have concluded that TbX (X = N, O, S and Se) are metallic in the NaCl phase. The results obtained in this work show that the theoretical parameters of the ground state, structure of the bands, density of the states (DOS) and optical properties agree well with other available theoretical and experimental data.

First-principles Calculations of Structural, Magnetic Electronic and Optical Properties of Rare-earth Metals TbX (X=N, O, S, Se)

Profile analysis of powder neutron diffraction data: Its scope, limitations, and applications in solid state chemistry

Publisher Summary Stimulated by technological prospects of high-density magneto-optical (MO) recording and by fundamental research on magnetism, a wealth of experimental data on MO Kerr spectra had been collected until the beginning of the nineties. The theoretical explanation of magneto-optical Kerr effect (MOKE) spectra because of first-principles band-structure calculations was at that time in its infancy, and consequently all the insight that theory could give in the microscopic mechanism leading to large Kerr rotations was mainly speculative, because nothing could be proven by first-principles calculations. This situation has profoundly changed, due to the rapid development of first-principles computational research on MO Kerr spectra during the nineties.

Chapter 3 Magneto-optical kerr spectra

CeSe and CeTe are found by neutron diffraction to be type-II antiferromagnets with the moment along the propagation vector. The phase transitions are continuous with the critical exponent for the magnetization $\ensuremath{\beta}=0.36\ifmmode\pm\else\textpm\fi{}0.02$. This constitutes a violation of the $\ensuremath{\epsilon}$-expansion predictions of Bak, Krinsky, and Mukamel, which hitherto have been successfully applied to a number of $ng~4$ systems and according to which the transitions should be of first order.

Magnetic Ordering in Cerium Monochalcogenides: A Test Case forεExpansions withn=4

Publisher Summary This chapter discusses the spectroscopic aspect of magneto-optics with the goal to relate the experimentally determined magneto–optical spectra to electronic transitions and provides directions for searching for improved magneto–optical materials. The analysis of the magneto–optical activity of a substance is generally carried out in two stages: first, the measured quantities like the Kerr rotation and ellipticity are related to the dielectric tensor or the conductivity tensor. In a second step, these functions are then interpreted in terms of band-structure features or may even be calculated directly from relativistic and spin-polarized band-structure calculations. The chapter reviews Faraday spectra and polar magneto-optical Kerr effect spectra, and a few times, Voigt effect and equatorial and longitudinal Kerr effect spectra. In the Faraday configuration, for which the field direction is parallel to the light propagation direction, the linearly polarized wave can be decomposed into a right- and a left-hand circularly polarized wave. The rotation of the plane of polarization indicates a phase shift between the two partial waves. The Faraday rotation is, therefore, a magnetic circular birefringence.

Chapter 2 Magneto-optical spectroscopy of f-electron systems

The magnetic structures and ordered moments have been determined at 4.2K for the metallic antiferromagnets CeS, NdS, NdSe, NdTe, and TbSe with NaCl structure by means of neutron diffraction. In contrast to the monopnictides, the monochalcogenides of both light and heavy rare earths have FCC type II antiferromagnetic ordering at low temperatures similar to FeO and MnO. Except NdS, where the magnetic moments are tilted by 24 degrees out of the (111) direction, the moments point along the inversion triad which leads to rhombohedral symmetry of the magnetic structure (Shubnikov group R13c). As a consequence of magnetoelastic interactions the FCC lattice of TbSe is rhombohedrally distorted at 4.2K.

https://iopscience.iop.org/article/10.1088/0022-3719/7/11/017/pdf

A. Niggli

Papers

Magnetic ordering of rare earth monochalcogenides. I. Neutron diffraction investigation of CeS, NdS, NdSe, NdTe and TbSe