K. Tomala

Magnetic properties of ErRu2Si2, ErOs2Si2 and DyRu2Si2

Abstract ErRu 2 Si 2 , ErOs 2 Si 2 and DyRu 2 Si 2 have been investigated by magnetization, neutron diffraction and Mossbauer measurements. These intermetallics were shown to order magnetically at low temperature and to exhibit metamagnetic-like behaviour. ErRu 2 Si 2 if T N = 5.7 K and ErOs 2 Si 2 ( T N = 4.7 K ) present sine-modulated magnetic structures characterized by a wavevector Q = ( q x , 0, 0) with q x = 1 5 (Ru) and 5 17 (Os). In both compounds the moments are aligned along the b -axis and a partial squaring of the modulation was inferred from Mossbauer and neutron diffraction measurements performed at 1.6 K. DyRu 2 Si 2 orders at T N = 29 K with a sine-wave modulation, Q = ( 2 9 , 0, 0) , of the moments parallel to the c -axis. A squaring up of the magnetic occurs at about 19 K it is complete at 1.6 K where μ Dy = 10 μ B , in agreement with the Mossbauer data.

Magnetic and crystal field properties of DyFe2Si2 from 161Dy Mössbauer study

Abstract A detailed 161 Dy Mossbauer study has been performed on DyFe 2 Si 2 . The hyperfine interaction parameters at low temperatures reveal that the crystal field ground state was a fairly pure | ± 15/2〉 Kramers doublet. This allowed one to conclude that the modulated spin structure deduced from the neutron data should be squared at saturation, and that the Dy 3+ -ions carry a magnetic moment of 10 μ B aligned parallel to the tetragonal c -axis. The energies of the low lying excited Kramers doublets, as well as the second- ( B 0 2 )and fourth-order ( B 0 4 )crystal field parameters, have been estimated from the analysis of the temperature dependence of the hyperfine field and quadrupole interaction found in the paramagnetic state.

Magnetic properties of ErPd2Si2 from magnetization Mössbauer and neutron diffraction measurements

Abstract Magnetization, neutron diffraction and 166 Er Mossbauer measurements on ErPd 2 Si 2 are reported. Below 4.8 K ErPd 2 Si 2 orders AF with complex modulated magnetic structures, where the Er moments are aligned along the c -axis. At 1.5 K a squared structure with μ Er ≈ 7.8(1)μ B is found while a saturation Er moment of 8.2(2)μ B is inferred from the hyperfine field data. The temperature dependence of the Mossbauer spectra in the paramagnetic region is explained in the framework of a relaxation model implying excited crystal field levels. Its analysis is used to estimate the B m n CEF parameters.

Magnetic properties of DyIr2Si2 and ErIr2Si2

Abstract DyIr 2 Si 2 and ErIr 2 Si 2 (ThCr 2 Si 2 structure type) have been investigated by magnetization, neutron diffraction and Mossbauer measurements with the 166 Er and 193 Ir resonances. These intermetallics were shown to order antiferromagnetically at 40 K (Dy) and 10 K (Er) and to exhibit metamagnetic behaviour. The AF order is of type I for both compounds, with the Dy moments (10μ B ) pointing along the c -axis and the Er moments (8.76μ B ) in the basal plane.

Magnetic properties of DyIr2Si2(I) from Mössbauer spectroscopy and magnetisation measurements

Abstract DyIr 2 Si 2 (ThCr 2 Si 2 structure type) has been investigated by magnetisation measurements and by Mossbauer spectroscopy with the 161 Dy and 193 Ir resonances. The compound was shown to order antiferromagnetically at 40 K and to exhibit metamagnetic-like behaviour. The analysis of the 161 Dy hyperfine interaction data allowed to estimate the crystal ( B 0 2 , B 0 4 ) and molecular field parameters. The Dy moments of 10μ B were shown to point along the tetragonal c -axis. From the absence of any transferred field at the 193 Ir nuclei it was anticipated that DyIr 2 Si 2 orders with a type I antiferromagnetic structure.

Mössbauer study of the NpSb1−xTex solid solutions

Abstract237Np,121Sb and125Te Mössbauer experiments on NpSb1−xTex (0≤x≤0.25) are reported. The data indicate the occurrence of Np3+ ions and suggest that the magnetic structure changes from AF-type I to AF-type IA (or ferri++-) by substituting Sb with 5% of Te. The Np ordered moment decreases smoothly with increasing Te content.

Isomer shifts of sp impurities in metallic hosts

Isomer shifts for119Sn and121Sb impurities in different metallic hosts are compared. In the frame of the Miedema and van der Woude model three contributions to the isomer shifts due to the charge transfer, electron density mismatch and volume adjustment are calculated.