Abstract
Three CeNi x Sn 2 compounds of different nominal Ni concentrations ( x = 0.65, 0.75, 0.85) were studied by high resolution neutron diffraction. The refinement of the nuclear structure shows that these compounds are single phase and that the actual compositions are close to the nominal ones. Low temperature neutron data of the CeNi 0.85Sn 2 compound [refined to x = 0.864(2)] confirm the mictomagnetic behaviour already observed in a previous sample ( I) refined to x = 0.840(4): coexistence of domains of two distinct magnetic phases in equal amounts. The relative amount of the two domains depends on x. One of these phases is ferromagnetic, q 1 = 0 with T C = 3 K. The other phase is a modulated antiferromagnet (antiphase domain type with two amplitudes) with T N = 4.0 K . Its magnetic ordering can be described by two propagation vectors q 2 = (010) ( C p magnetic lattice) and q 3 = 1 3 b ∗. The ordered magnetic moment valueat 1.5 K in both phases is 2.0 μ B /Ce atom and the moments point into the same direction, along c. In sample ( I) the two phases were present in equal amounts while in the present sample the amount of the ferromagnetic phase is strongly reduced to approximately 16%. The magnetic properties of these compounds and of compounds with higher and lower nominal Ni concentrations have been studied by us in more detail by means of measurements of specific heat, the magnetisation, the AC and DC susceptibility. In several cases two magnetic phase transitions were observed. The nature of these transitions is discussed in the light of the low-temperature neutron diffraction results obtained for the more Ni-rich samples.
Published Version
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