Synchrotron x-ray study of lattice vibrations in CdCr2O4

Using inelastic x-ray scattering we have investigated lattice vibrations in a geometric frustrated system CdCr2O4 that upon cooling undergoes a spin-Peierls phase transition at TN = 7.8 K from a cubic and paramagnetic to a tetragonal and Neel state. Phonon modes measured around Brillouin zone boundaries show energy shifts when the transition occurs. Our analysis shows that the shifting can be understood as the ordinary effects of the lowering of the crystal symmetry

First-principle computations of ferromagnetic HgCr2Z4 (Z = S, Se) spinels for spintronic and energy storage system applications

We explored electronic spin-dependent physical aspects of ferromagnetic HgCr2Z4 (Z = S, Se) spinels using density functional theory (DFT) for spintronic and energy storage applications. In calculations of structural, electronic, magnetic, and transport aspects, we used Perdew-Burke-Ernzerhof generalized gradient approximation (PBEsol GGA) plus modified Becke-Johnson (mBJ) potential. To calculate structural parameters, we optimized both spinels in the ferromagnetic phase and our predicted data of structural parameters show good comparison with existing experimental data. Also, the calculated negative formation energy confirms the structural stability of the studied spinels. Analyzingferromagnetic nature of studied spinels based on exchange splitting energy and magnetic parameters, we used mBJ potential to calculate band structure (BS) and density of states (DOS). By exploring DOS, we found the dominant role of electrons spin has been shown by negative indirect exchange energy Δx(pd) values and the fulfillment of the condition Δx(d) >ΔEcry. In addition, exchange constants (N0α and N0β) and magnetic moments were also calculated to ensure their ferromagnetism in studied spinels. Further, the exploration for the influence of electrons spin on electronic transport aspects has been done by investigating electrical and thermal conductivities, Seebeck coefficient, and power factor by using classical Boltzmann transport theory

Die Subsidiarität des Verwaltungsstrafrechts gegenüber dem gerichtlichen Strafrecht

von Bettina ZwinscherQuellen- und Literaturverzeichnis: Blatt I-IIUniversität Salzburg, Diplomarbeit, 2019(VLID)506714

Study of lattice dynamics in the CuIr 2S 4 system

The lattice dynamics in the CuIr2S4 system have been investigated through Raman spectroscopy and the induced-pressure effect. Four Raman active modes are observed experimentally. Upon cooling, these Raman spectra undergo changes due to the Peierls-like phase transition. In addition, the substitution of Ag for Cu affects the amplitude of the Raman spectra while keeping their wave number unchanged. Furthermore, the positive and negative pressure effects are induced by shrinking and expanding the lattice. It is suggested that the pressure effect is an effective proof of the orbital-induced Peierls state mechanism