Ch.D. Routsi

Magnetic characteristics of some RNiSn (R = Ce, Pr, Nd, Sm) and RRhSn (R = Ce, Pr, Nd) compounds

Abstract Magnetic properties of seven equiatomic ternary RNiSn and RRhSn compounds (R = light rare earth) have been studied in fields of up to 20 kOe in the temperature range 4.2–200 K. It has been found that all compounds follow the Curie-Weiss law above 40 K, except CeNiSn and CeRhSn which do not show Curie-Weiss behavior at any temperature. The latter show a Kondo or valence fluctuation behavior. The compound SmNiSn orders antiferromagnetically with a Neel temperature ≃ 9 K. No ordering temperature was observed down to 4.2 K for the rest of the compounds.

MAGNETIC PROPERTIES OF THE EQUIATOMIC TERNARY RTSN COMPOUNDS (R=RARE EARTH, T=PT, RH)

Abstract Magnetic susceptibility studies on the hexagonal ternary equiatomic RTSn (R = rare earth and Y; T = Pt, Rh) compounds have been realized. These compounds are isostructural to Fe2P with space group P 6 2m. The ordering temperatures of all compounds are smaller than 19 K. The susceptibility of YTSn is temperature independent.

Magnetic characteristics of some RNiSn ternary equiatomic alloys

Abstract Magnetic properties of seven equiatomic ternary RNiSn compounds (R = heavy rare earth and Y) have been studied in fields of up to 20 kOe in the temperature range 4.2–200 K. It has been found that all compounds, which belong to the orthorhombic TiNiSi-type structure, are paramagnetic above 40 K. YNiSn presents a temperature-independent susceptibility and the moment of nickel was found to be zero in the whole series. The compounds with Gd, Tb and Dy are antiferromagnetic at low temperatures. No ordering temperature was observed down to 4.2 K for the compounds with Ho, Er and Tm.

Unusual magnetic behavior in TbCo3Ga2 and ErCo3Ga2 compounds

Abstract ZFC and FC magnetization measurements were performed on the ternary RCo 3 Ga 2 (R = Tb, Er) hexagonal compounds. A crystallographic site of these compounds is partially occupied by Co and Ga atoms respectively. Pronounced maxima for TbCo 3 Ga 2 and minima for ErCo 3 Ga 2 were observed in the ZFC magnetization. Hysteresis loops, the temperature dependence of the coercive field and the time dependence of remanence prove a probable existence of a spin-glass-like behavior.

Magnetic properties of RA3Ga2 compounds (R=rare earth, A=Co, Ni)

Abstract The crystal structure and the magnetic properties of the RA3Ga2 compounds have been studied from 4.2 to 300 K under magnetic fields in the region of 1 to 20 kOe. YNi3Ga2 is a Pauli paramagnet while YCo3Ga2 shows a ferromagnetic behavior. The RNi3Ga2 compounds are ferromagnetic. At low temperatures the RCo3Ga2 compounds under 1 kOe show a maximum in the susceptibility vs. temperature curves. ErCo3Ga2 and TmCo3Ga2 have a compensation point at 105 and 111 K respectively. They are probably ferrimagnetic. The compounds with A = Co show hysteresis effects, especially in the 4.5 K isotherms.

Magnetic structures of PrCO2Si2 and TbCo2Si2 compounds

Abstract Neutron diffraction studies of polycrystalline PrCo2Si2 and TbCo2Si2 compounds were carried out at 4.2 and 293 K. Both samples have collinear antiferromagnetic order below TN(31(1) and 46(1) K for Pr and Tb compound respectively), with their magnetic moments parallel to the c axis. The ordered magnetic moment values of Pr and Tb at 4.2 K (3.19 and 9.12 μB respectively), are close to the saturation value of the free ions. The corresponding magnetic space group Pl4/mnc (Sh410128) is body-anticentered ( k = 111 222 refering to Pl cell).

The sine-modulated and antiphase-type structures of TbNiSn

Abstract The Neel temperature of the TbNiSn orthorhombic compound, space group Pnma, is 20 K. Below this temperature, a sine-modulated magnetic structure is formed. The compound then forms an antiphase-type structure below its 7 K transition temperature. The magnetic propagation vector has two components in the plane perpendicular to the c -axis, and the magnetic moments are parallel to the b -axis with 9μ B for both types of structure. TbNiSn is also a metamagnet.

The antiferromagnetic structure of ErCo2Si2 by neutron diffraction

Abstract The magnetic structure of the tetragonal ErCo 2 Si 2 compound is determined by neutron diffraction on powder sample at 4.2 K. The magnetic ordering is connected with a symmetry lowering, magnetic space group P 2s 1 (Sh 7 2 ) k = 000. The structure is collinear antiferromagnetic with the erbium magnetic moments making an angle of 56.2° with the c axis. The magnetic moment value for erbium is 6.75μ B .

Amplitude-modulated type structure of HoNiSn

Abstract HoNiSn compound crystallizes in the orthorhombic Pnma space group. It is antiferromagnetic with ordering temperature below 4.2 K. This compound, at 1.4 K, has an incommensurate magnetic propagation vector k = [0.3593, 0.3337, 0.0]. The holmium magnetic moment maximum value is 8.5μ B and its direction forms an angle of 75° with the a -axis. The nickel moment is zero. The HoNiSn magnetic structure is of a sine-modulated amplitude type. Both directions of the moment and the propagation vector lie on the ( a, b ) plane.

Magnetic properties of RCo4Ga (R = Ce, Pr, Gd, Tb, Dy, Y) and RCoGa4 (R = Ce, Pr, Nd)

Abstract The magnetic properties of the RCo 4 Ga (R = Ce, Pr, Gd, Tb, Dy, Y) and RCoGa 4 (R = Ce, Pr, Nd) compounds have been studied from 4.2 to 300 K under magnetic fields from 1 to 20 kOe. YCo 4 Ga, CeCo 4 Ga and PrCo 4 Ga show ferromagnetic behavior while GdCo 4 Ga, TbCo 4 Ga and DyCo 4 Ga compounds are ferrimagnetic. At low temperatures under 1 kOe, the RCo 4 Ga compounds (except GdCo 4 Ga and YCo 4 Ga) show a maximum in the magnetization versus temperature curves. Hysteresis effects are also present. The RCoGa 4 compounds (R = Ce, Pr, Nd) present paramagnetic behavior down to 4.6 K.