Magnetic anisotropy of Ni modified by extreme lattice expansion

The induced magnetism of isolated (Cd) adatoms, soft-landed onto ultrathin Ni layers grown pseudo-morphologically on Pd(001) (a_Pd = 3.8907 Å), was studied using the perturbed angular correlation (PAC) technique. The magnitude of the induced magnetic response (magnetic hyperfine field of |5.2| T) was found to be ca. 30% smaller than on bulk Ni (a_Ni = 3.524 Å) surfaces. This result is compared to ab initio calculations. Additionally, the magnetic anisotropy of the induced response was found to be modified as compared to bulk Ni surfaces and the induced hyperfine field was observed to emerge from the plane at an angle of 50(5)^○ to the surface normal. This canted magnetic anisotropy is attributed to the large lattice expansion of the ultrathin Ni film on Pd(001).     

Magnetic hyperfine field for arsenic in nickel

The magnetic hyperfine field for As in nickel has been remeasured by DPAD techniques. Using a sandwich type of target the excited As nuclei were recoil-implanted into unpolarized nickel layers after the reaction⁷¹Ga (α, n)⁷⁴As. The resultH _hf (300 K)=106 (2) kOe differs considerably from a former IPAC measurement.     

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.     

Nuclear polarization of high-spin levels and the sign of the quadrupole moment of 54Fe(10+)

The determination of the sign of the quadrupole deformation at high spins requires an observation of the electric quadrupole interaction of polarized isomers in single crystals of non-cubic metallic hosts. The ⁵⁴Fe(10⁺) isomer was polarized, subsequent to its population by the (¹²C, p2n) reaction, by passage through an array of tilted carbon foils. The isomers were then recoil implanted into single crystals of zinc and cadmium and the tune differential modulations of the angular distribution of decay γ-rays were observed. Nuclear polarization values of P_I = 0.08(3)?0.18(5) were found for 13–17 polarizing foils, respectively, and a positive sign of the quadrupole moment was deduced. An improved value was established for the quadrupole moment: $\text{Q[}{}^{54}\text{Fe}\text{(10}{}^{\mathrm{+}}\text{)] = + 29.7(4) e ·}\text{fm}{}^2$, in agreement with current shell-model predictions.     

Theg-factor of the Iπ=5/2+ isomer in77Br

The g-factor of the t_1/2=9.3 ns, I_π=5/2 + state at E_x=130 keV in⁷⁷Br has been measured by observation of the time differential perturbed angular correlation (PAC) in a Co single crystal. The experimental value g=1.32(1) gives evidence for large deformation, which is discussed in the framework of triaxial-rotor-plus-particle models.     

Temperature dependence of the Knight shift for cadmium in palladium

The Knight shift and its temperature dependence for a Cd impurity in palladium metal were measured by means of DPAD- and DPAC-methods utilizing the well known 5/2⁺, 247-keV state in¹¹¹Cd. The shift at 80 K was found to be KS (CdPd, 80 K)=?0.8(2)%. The observed variation of the KS in the temperature range from 80 K up to 1400 K is 0.5%. For calibration purposes an accurate remeasurement of the magnetic moment of the 5/2⁺ state in¹¹¹Cd was necessary and yieldedμ(¹¹¹Cd, 5/2⁺, 247 keV)=?0.7697(20) n.m.     

First in-beam observation of97Ag — The three-proton-hole spectrum in100Sn

Excited states in⁹⁷Ag have been identified for the first time following the reactions⁴⁶Ti(⁵⁸Ni,α p 2n and⁶⁴Zn(³⁶Ar,p 2n. The population cross sections were 1.0(5) mb and 0.7(3) mb, respectively. Theγ-decay of the seniorityΝ=3 states below theI ^π=(17/2^?) and (21/2⁺) isomers was investigated. In a search for short lived isomers half lives oft _1/2=5(2) ns and 2.5(5) ns were found in theN=50 isotones⁹⁷Ag,I ^π=(17/2^?) and/or (21/2⁺) and⁹⁵Rh,I ^π=(21/2⁺). A new isomer was identified in⁹⁷Pd,I ^π=17/2⁺ witht _1/2=2.3(5) ns. The implication of the three-proton hole spectrum in¹⁰⁰Sn for the empirical residual interaction and shell model predictions is discussed.     

Magnetic hyperfine field for zinc in nickel

Electron mobility in the narrow band solid with a cellular disorder is investigated by methods of the coherent potential theory. Numerical results for the tight-binding model with the Lorentzian distribution of site potentials are presented. The motion of the electron in the region of extended states is neither a well defined coherent band motion nor a simple Brownian diffusion. The statistical electron-hole correlation proves to be important and increases fast with the potential distribution width to band width ratio. The correlation also increases when approaching the mobility edges.     

Magnetic hyperfine field for zinc in iron

The magnetic hyperfine field for zinc in iron has been measured by the DPAD method following the reaction ⁶⁴Ni(α, n)⁶⁷Zn^m. Measurements performed with a sandwich target and with ⁶⁴Ni($\text{Fe}$) alloy targets containing 3% and 6% nickel yielded similar results: H_hf(0) = -191 ± 3 kG.