Hyperfine Interaction Studies on Y, Zr, Nb, Mo, Rh, In and Xe in Co

Nuclear magnetic resonance on oriented nuclei and modulated adiabatic fast passage on oriented nuclei measurements were performed on several 4d and 5sp impurities in polycrystalline Co(fcc) foils and Co(hcp) single crystals. The hyperfine fields of Y and Zr in Co(fcc), the hyperfine fields of Y, Zr, Nb, Mo, Rh, In and Xe in Co(hcp), the electric field gradients of Zr, Nb and In in Co(hcp), and the nuclear spin-lattice relaxations of Zr, Nb, Rh and In in Co(hcp) were determined. The dependence of the hyperfine fields and electric field gradients in Co(hcp) on the angle between the magnetization and the c axis was investigated in most cases. The magnetic-field dependence of the spin-lattice relaxation was studied for Nb, Rh and In in Co(hcp), applying the magnetic field perpendicular to the c axis. The known hyperfine interaction parameters of the 4d and 5sp impurities in Co(fcc) and Co(hcp) are summarized. The new results provide a more detailed picture of the hyperfine interaction in Co.     

Surface and interface studies with ASPIC

Magnetic properties at surfaces and interfaces have been investigated performing Perturbed Angular Correlation (PAC) measurements in the UHV chamber ASPIC (Apparatus for Surface Physics and Interfaces at CERN) using different PAC probes. The results are: (i) determination of magnetic hyperfine fields of Se on Fe, Co, Ni which are explained by a theoretical study on the magnetic hyperfine fields of 4sp-elements in adatom position on Ni and Fe;(ii) static magnetic hyperfine fields in ultrathin Pd on Ni(0 0 1) which indicate an induced magnetic order in Pd;(iii) the observation of induced fluctuating magnetic interactions in Pd when thick Pd is in contact with Ni. Monolayer-resolved measurements of the magnetic hyperfine fields in magnetized Pd are in accordance with theoretical predictions of the layer dependence of the induced magnetic moments in Pd. This revised version was published online in July 2006 with corrections to the Cover Date.     

COMPLIS experiments: COllaboration for spectroscopy Measurements using a Pulsed Laser Ion Source

Laser spectroscopy measurements have been carried out on very neutron-deficient isotopes of Au, Pt and Ir, produced as daughter elements from a Hg ISOLDE beam. For these transitional region nuclides, the hyperfine structure (HFS) and isotope shift (IS) were measured by Resonance Ionization Spectroscopy (RIS). Magnetic moments μ, spectroscopic quadrupole moments Q_s and changes of the nuclear mean square charge radius δ〈r_c ²〉along isotopic series have been extracted. For some results, a detailed comparison with theoretical predictions is presented. This revised version was published online in July 2006 with corrections to the Cover Date.     

High-resolution measurements of low-energy conversion electrons

High-resolution measurements of low-energy conversion electrons have been performed in odd and odd–odd nuclei with masses around A=182. The experimental setup, a magnetic spectrograph coupled to a specific tape transport system, is described. Three experiments have been performed and the main results are presented. This revised version was published online in July 2006 with corrections to the Cover Date.     

Electric field gradients of acceptor–donor pairs in semiconductors

The interaction between substitutional and interstitial donors and single or double acceptors in Si, GaAs, InP, and InAs has been studied by perturbed angular correlation spectroscopy (PAC). For the case of Si, complex formation between substitutional donors (As, P) and different radioactive acceptors (¹¹¹In, ¹¹¹Cd, ¹¹⁷Cd) has been observed. The formation of Cd–hydrogen pairs using either ¹¹¹Cd or ¹¹⁷Cd is discussed for GaAs, InP, and InAs. This revised version was published online in August 2006 with corrections to the Cover Date.     

Electric field gradient and atomic position for Se in MoSe2

Hyperfine Interactions - We have measured the nuclear quadrupole interaction at 77Se in the layer compound semiconductor MoSe2 by γ–γ PAC in the decay of 77Br following...