M. Braden

Effect of Structural Parameters on Superconductivity in Fluorine-Free LnFeAsO1-y (Ln = La, Nd)

The crystal structure of LnFeAsO 1- y (Ln = La, Nd) has been studied by the powder neutron diffraction technique. The superconducting phase diagram of NdFeAsO 1- y is established as a function of oxygen content which is determined by Rietveld refinement. The small As–Fe bond length suggests that As and Fe atoms are connected covalently. FeAs 4 -tetrahedrons transform toward a regular shape with increasing oxygen deficiency. Superconducting transition temperatures seem to attain maximum values for regular FeAs 4 -tetrahedrons.

EVIDENCE FOR INCOMMENSURATE SPIN FLUCTUATIONS IN SR2RUO4

We report first inelastic neutron scattering measurements in the normal state of Sr_2RuO_4 that reveal the existence of incommensurate magnetic spin fluctuations located at

Structural and magnetic aspects of the metal-insulator transition in Ca 2 − x Sr x RuO 4

{\bf q}_0=(\pm 0.6\pi/a, \pm 0.6\pi/a, 0)

Crystal and magnetic structure of LaTiO 3 : Evidence for nondegenerate t 2 g orbitals

. This finding confirms recent band structure calculations that have predicted incommensurate magnetic responses related to dynamical nesting properties of its Fermi surface.

Magnetoelastic coupling in RETiO3 (RE = La, Nd, Sm, Gd, Y)

The phase diagram of

Inelastic neutron scattering study of magnetic excitations in Sr 2 RuO 4

{\mathrm{Ca}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{RuO}}_{4}

CaCrO3: an anomalous antiferromagnetic metallic oxide.

has been studied by neutron diffraction on powder and single-crystalline samples. The experiments reveal antiferromagnetic order and structural distortions characterized by tilts and rotations of the

Crystal and magnetic structure of the oxypnictide superconductorLaFeAsO1−xFx: A neutron-diffraction study

{\mathrm{RuO}}_{6}

Bond-stretching-phonon anomalies in stripe-ordered La1.69Sr0.31NiO4.

octahedra. There is strong evidence that the structural details of the isovalent samples tune the magnetic as well as the electronic behavior. In particular we observe for low Sr concentration a metal-insulator transition associated with a structural change and magnetic ordering.

Low temperature phase transition and superconductivity in (La Nd)SrCuO

The crystal and magnetic structures of LaTiO 3 have been studied by x-ray and neutron-diffraction techniques using nearly stoichiometric samples. We find a strong structural anomaly near the antiferromagnetic ordering T N = 146 K. In addition, the octahedra in LaTiO 3 exhibit an intrinsic distortion, which implies a splitting of the t 2 g levels. Our results indicate that LaTiO 3 should be considered as a Jahn-Teller system where the structural distortion and the resulting level splitting are enhanced by the magnetic ordering.