Chalk River Laboratories

About: Chalk River Laboratories is a based out in . It is known for research contribution in the topics: Neutron diffraction & Neutron scattering. The organization has 2297 authors who have published 2700 publications receiving 73287 citations.

Oxygen induced broadening effects studied by RBS and SIMS

Abstract: The redistribution of As from a shallow As-implant (5 keV) in Si following oxygen bombardment has been studied by grazing exit RBS. The oxygen bombardment was performed in an ion implanter (12.5 keV O+, room temperature and 40 K), and a reactive ion elcher (1.7 keV O+2). For 12.5 keV O+ bombardment the As redistributes very rapidly in the sample; displacements up to 50 nm are observed. Implantation at 40 K shows only a very small reduction in spreading of the As distribution indicating a very low activation energy for the defect-induced diffusion. Bombardment with 1.7 keV O+2 does not broaden the internal As distribution as much as at 12.5 keV O+ but our results indicate that the As-atoms segregate at the oxide-silicon interface. Enhanced segregation in the reactive ion etcher results in a much larger decay length than under SIMS-bombardment conditions.

The Effect of Interlayer Cations on the Magnetic Properties of the Mixed-Metal Pnictide Oxides: A2MnZn2As2O2 (A = Sr, Ba)

Abstract: The new pnictide oxide Sr2MnZn2As2O2 is reported. The crystal structure of this compound consists of a 1:1 intergrowth of square-planar MnO22- layers and ThCr2Si2-type Zn2As22- layers interspersed by Sr cations. This compound has been prepared by sintering the stoichiometric ratio of SrO, Mn, Zn, and As in a fused-silica ampule under 0.2 atm of Ar at 1000 °C for 1 week. The sample quality has been examined by Rietveld refinement of the powder X-ray diffraction data, and the transition metal site (2a and 4d) selectivity has been analyzed by Rietveld refinement of powder neutron diffraction data. Furthermore, effects of this structural order on the magnetic susceptibility and interaction between the magnetic layers have been analyzed by temperature-dependent magnetization measurements. The magnetic structures of both phases, A2MnZn2As2O2 (A = Sr, Ba), have been investigated by temperature-dependent powder neutron diffraction. The Ba analogue exhibits two-dimensional short-range order below about 40 K, where...

Incommensurate dynamic correlations in the quasi-two-dimensional spin liquid BiCu 2 PO 6

Abstract: We report detailed inelastic neutron-scattering measurements on single crystals of the frustrated two-leg ladder ${\text{BiCu}}_{2}{\text{PO}}_{6}$, whose ground state is described as a spin liquid phase with no long-range order down to 6 K. Two branches of steeply dispersing long-lived spin excitations are observed with excitation gaps of ${\ensuremath{\Delta}}_{1}=1.90(9)$ meV and ${\ensuremath{\Delta}}_{2}=3.95(8)$ meV. Significant frustrating next-nearest-neighbor interactions along the ladder leg drive the minimum of each excitation branch to incommensurate wave vectors ${\ensuremath{\zeta}}_{1}=0.574\ensuremath{\pi}$ and ${\ensuremath{\zeta}}_{2}=0.553\ensuremath{\pi}$ for the lower and upper energy branches, respectively. The temperature dependence of the excitation spectrum near the gap energy is consistent with thermal activation into singly and doubly degenerate excited states. The observed magnetic excitation spectrum as well as earlier thermodynamic data could be consistently explained by the presence of strong anisotropic interactions in the ground-state Hamiltonian.