M. Hoinkis

Fermi surface and electron correlation effects of ferromagnetic iron

The electronic band structure of bulk ferromagnetic iron is explored by angle-resolved photoemission for electron correlation effects. Fermi surface cross-sections as well as band maps are contrasted with density functional calculations. The Fermi vectors and band parameters obtained from photoemission and their prediction from band theory are analyzed in detail. Generally good agreement is found for the Fermi surface. A bandwidth reduction for shallow bands of ~ 30 % is observed. Additional strong quasiparticle renormalization effects are found near the Fermi level, leading to a considerable mass enhancement. The role of electronic correlation effects and the electronic coupling to magnetic excitations is discussed in view of the experimental results.

Spin-Peierls transition in TiOCl

Temperature-dependent x-ray diffraction of the low-dimensional spin-

Possible pressure-induced insulator-to-metal transition in low-dimensional TiOCl

1∕2

Are the renormalized band widths in TTF-TCNQ of structural or electronic origin? - An angular dependent NEXAFS study

quantum magnet TiOCl shows that the phase transition at

Unoccupied electronic structure of TiOCl studied using x-ray absorption near-edge spectroscopy

{T}_{c2}=90\phantom{\rule{0.3em}{0ex}}\mathrm{K}

Cluster dynamical mean-field calculations for TiOCl

corresponds to a lowering of the lattice symmetry. Below

Spin dynamics in the low-dimensional magnet TiOCl

{T}_{c1}=66\phantom{\rule{0.3em}{0ex}}\mathrm{K}

Electronic structure of the spin- 1 2 quantum magnet TiOCl

a twofold superstructure develops, that indicates the formation of spin-singlet pairs via direct exchange between neighboring Ti atoms, while the role of superexchange is found to be negligible. TiOCl thus is identified as a spin-Peierls system of pure one-dimensional chains of atoms. The first-order character of the transition at

Heat capacity of the quantum magnet TiOCl

{T}_{c1}

Muon-spin relaxation measurements on the dimerized spin-1/2 chains NaTiSi2O6 and TiOCl

is explained by the competition between the structurally deformed state below