P.A. Kotsanidis

Magnetic properties of the ternary rare earth silicides R2PdSi3 (R = Pr, Nd, Gd, Tb, Dy, Ho, Er, Tm and Y)

Abstract The magnetic properties of R 2 PdSi 3 compounds, where R is Pr, Nd, Gd, Tb, Dy, Ho, Er, Tm and Y, have been investigated from 4.2 to 300 K. Pr 2 PdSi 3 does not show any magnetic ordering temperature down to 4.2 K. Nd 2 PdSi 3 is ferromagnetic with a Curie temperature of 16 K. The heavy rare earth compounds show magnetic ordering temperatures in the region between 8 and 21 K, except the compound with Tm for which the ordering temperature must be lower than 4.2 K. Y 2 PdSi 3 is a nonmagnetic compound.

Magnetic structure of the TbNiC2 ternary carbide

Abstract The magnetic structure of the TbNiC 2 ternary carbide was studied by neutron diffraction. The crystal structure of this compound is orthorhombic, space group Amm2, with Neel temperature equal to 25 K. The magnetic cell, at 16 K, is four times larger than the chemical one, with a wave vector k = [ 1 2 1 2 0] . The terbium moment value and direction are μ Tb = 6.8μ B along the c -axis of the crystal. The crystal field calculations on the Tb 3+ site with a molecular field parallel to c , give a magnetic model which agrees with the observed one.

Magnetic structure determination of NdNiC2 and TmNiC2 by neutron diffraction

Isostructural orthorhombic NdNiC2 and TmNiC2 reveal collinear antiferromagnetic structures with magnetic propagation vectors [12120] and [0, 0, 1], respectively. In NdNiC2, ferromagnetic (110) planes are coupled pairwise in opposite spin orientations; in TmNiC2, adjacent ferromagnetic (001) planes are coupled antiferromagnetically. The magnetic moments are oriented parallel to the a-axis and have values of 2.7μB (Nd) and 3.3μB (Tm) at 4 K.

The antiferromagnetic structure of ErNiC2 ternary carbide

Abstract The magnetic structure of the orthorhombic ErNiC 2 ternary compound was studied by neutron diffraction. The structure is collinear antiferromagnetic. The Neel temperature is 8 K. The magnetic unit cell has the same dimensions as the chemical one with a magnetic propagation vector k = [0,0,1]. The erbium moments are oriented along the crystallographic a -axis and have a value of 8.7 μ B at 4.2 K.

Magnetic properties of RCoC2 (R = Y, Gd,Tb) compounds

Abstract The magnetic properties of YCoC 2 , GdCoC 2 and TbCoC 2 have been studied by means of susceptibility and neutron diffraction measurements. These properties are due only to the rare earth sublattice. TbCoC 2 is ferromagnetically ordered below 27 K with moment orientations along the crystallographic a -axis; the terbium moment is 8.4(2)μ B at 4.2 K.

The two-component non-collinear antiferromagnetic structures of DyNiC2 and HoNiC2

Abstract DyNiC 2 and HoNiC 2 , which crystallize in the orthorhombic space group Amm2, have been studied by neutron powder diffraction in the temperature range from 300 to 1.9 K. Both compounds exhibit modulated antiferromagnetic configurations of the rare earth magnetic moments. The magnetic transition temperatures are 10 and 4 K for DyNiC 2 and HoNiC 2 , respectively. The magnetic structures are described by two propagation vectors: the commensurate k 1 =[0, 0, 1] and the incommensurate k 2 =[ 1 2 −τ, 1 3 +τ, k z ] with τ=0.03 and 0 and k z =0.935 and 0.86 for DyNiC 2 and HoNiC 2 respectively. The magnitude and direction of the magnetic moments are determined. The resultant non-collinear antiferromagnetic spin configurations are discussed with respect to crystal field and magnetic exchange interactions.

Structural and magnetic properties of RCoC2 (R = Pr, Dy, Ho) compounds studied by neutron diffraction

Abstract PrCoC 2 , DyCoC 2 and HoCoC 2 have been studied by neutron powder diffraction in the temperature range from 300 to 1.6 K. PrCoC 2 crystallizes in monoclinic space group Cc, DyCoC 2 and HoCoC 2 is paramagnetic down Refined lattice and atomic positional parameters and interatomic distances are given. PrCoC 2 is paramagnetic down to 1.6 K. DyCoC 2 and HoCoC 2 order ferromagnetically at T C = 9 K . The ordered Dy and Ho moments are 6.0(5) and 6.6(1) μ B at 1.7 K respectively. The moments are oriented along the a -axis. No moment is observed on Co.

The sine-modulated magnetic structure of Dy5Sb3

Abstract Dy 5 Sb 3 crystallizes in the hexagonal Mn 5 Sb 3 -type structure. The compound orders antiferromagnetically at 69 K. The neutron diffraction diagram, realized at 2 K, shows, in addition to nuclear ones, peaks of magnetic origin which were indexed with a magnetic wave propagation vector k = [0, 0, 0.6758]. The values of the magnetic moments of the two dysprosium sites are 9.5 and 6.9μ B respectively. The magnetic moments are collinear in a direction forming an angle of 66° with the c -axis of the crystal.

Magnetic structures of rare earths R in RCoC2 and RNiC2 compounds

A comparative survey is given on the variety of magnetic structures of the series of RCoC2 and RNiC2 with R=Pr, Nd, Tb, Dy, Ho, Er and Tm, which have been analysed by neutron diffraction. Rare earth structure relevant features are summarized. All compounds, except those with Pr, order magnetically at low temperatures. Magnetic order is confined to the rare earths; Co and Ni sites remain non-magnetic. RCoC2 become ferromagnets; RNiC2 order antiferromagnetically in different spin configurations. The type of order and R dependent moment configurations are explained by RKKY exchange and additional crystal field interactions.

Modulated amplitude type of TbNiSn magnetic structure

Abstract Neutron diffraction of a polycrystalline sample of TbNiSn was performed at 40 and 12K. The compound has the orthorhombic Pnma crystal structure and presents a modulated amplitude type of magnetic structure with k = [0.313, 0.325, 0.0] and a spin axis parallel to b.