K. Kaczmarska

Magnetic properties and resistivity of CeM2X2 compounds (M Cu, Ni; X Sn, Sb)

Abstract The magnetic properties and resistivity of CeNi 2 Sn 2 , CeCu 2 Sn 2 and CeNi 2 Sb 2 allow us to classify these compounds as Kondo systems and to estimate the magnitude of the crystal field splittings and hybridization.

Electrical resistivity and magnetic properties of the Re1−xGdxAl2 laves phase (for Re: La, Lu, Y)

Abstract X-ray, magnetic, electrical resistivity and ESR studies of Re1-xGdxAl2 type compounds (Re - La, Lu, Y) were performed. The transition temperatures, effective moments, effective mass, lattice constants, crystallographic parameters, thermal broadening of resonance linewidth and g-factors were obtained. It was found that the simple RKKY model applied to describing the electrical resistivity and magnetic susceptibility in a large range of concentrations x seems to be right.

ESR in ternary GdT2Si2 systems (T = Co, Ni, Cu, Ru, Rh, Pd)☆

Abstract ESR spectra of GdT 2 Si 2 , T = 3d or 3d metal, have been measured in a paramagnetic state. It was found that g -shift and thermal broadening of the Gd 3+ resonance line “ b ” depends on the number of d-electrons in the band.

Structural, magnetic and ESR properties of (Gd-R)T2Sn2 compounds

Abstract Data are reported for new ternary RT 2 Sn 2 compounds (R=Gd, La, Lu, Y; T=Cu, Ni). All the investigated compounds crystallize in the primitive tetragonal CaBe 2 Ge 2 -type structure. GdCu 2 Sn 2 and GdNi 2 Sn 2 are antiferromagnetically ordered below 11 and 7K, respectively. Both compounds exhibit changes in magnetic structure at lower temperatures and in magnetic fields of about 30 kOe (T=Cu) and 20 kOe (T=Ni). Magnetic and ESR results indicate that Gd-Gd interactions are weaker in the Ni than in the Cu compounds. The marked ESR bottleneck effect in these two compounds was partly opened by replacing Gd by nonmagnetic impurities.

ESR in ternary GdT2Ge2 systems (T ≡ Co, Ni, Cu, Pd, Ag)

Abstract ESR spectra of GdT2Ge2 (T ≡ 3d or 4d transition metal) have been measured in the paramagnetic state. It was found that the compounds investigated are bottlenecked. The g shift and the thermal broadening of the linewidth depend on the number of transition metal d electrons.

Magnetic, resistivity and ESR studies of the compounds GdNi2Sb2 and GdCu2Sb2

Abstract Physical data are reported for the ternary compounds GdNi 2 Sb 2 and GdCu 2 Sb 2 . The compounds crystallize in the primitive tetragonal CaBe 2 Ge 2 -type structure. Both compounds are antiferromagnets with T N values of 6 and 11 K, respectively. Anomalies in magnetization curves, susceptibility and resistivity below T N can be attributed either to a magnetic structure change or to spin-flop phenomena. Frustration of magnetic interactions is highly probable in these systems. ESR results are discussed on the basis of features of the density of states deduced from X-ray photoemission spectra.

ESR in GdxRe1-xAl2 (Re=La, Lu, Y) - the experimental and the theoretical studies

Abstract The ESR measurements in Gd x Re 1- x Al 2 (Re=La, Lu, Y) in high concentration range are presented. The theoretical analysis of ESR data in the whole concentration range x ϵ (0,1), which explains consistently the observed positive g shifts in unbottlenecked region and negative g shifts in bottlenecked region exhibits unambigously the d-character of band electrons in these compounds.

The influence of Ni impurities on the magnetic properties and ESR in Gd(Al1−xNix)2 compounds for x ⩽ 0.2

Abstract X-ray, magnetic and ESR studies in Gd(Al 1− x Ni x ) 2 compounds were performed. The obtained results, analysed by means of the theoretical models proposed by P.A. Lindgard and E. Zipper show that nickel is nonmagnetic in the studied compounds and its presence changes the conduction band structure and decreases the density of states on the Fermi level.

Kondo properties of the new compounds Ce(AgxCu1-x)2-δSb2

Abstract Some physical properties of the new compound CeAg2-δSb2 and its solid solutions with CeCu2-δSb2 are reported. All investigated compounds are antiferromagnets. The magnetic structure of CeCu2-δSb2 is frustrated with propagation vector q = (0, 0, 1 2 ) , whereas CeAg2-δSb2 is nonfrustrated with q = (0.06, 0.06, 0).

The ESR bottleneck effect in Gd1 − xRExCu2Si2, Gd1 − xRExCu2Ge2 and Gd1 − xRExAg2Ge2 (RE ≡ Y, La, Lu)

Abstract The strong bottleneck effect in the compounds GdCu 2 Si 2 , GdCu 2 Ge 2 and GdAg 2 Ge 2 was partly opened by non-magnetic impurities. We found that the best impurities for opening the bottleneck are lanthanum and lutetium for systems with germanium and lanthanum for systems with silicon.