A powder diffraction measurement of Ho_5Rh_4Ge_{10} is reported. This compound crystallizes in the tetragonal Sc_5Co_4Si_{10}-type structure (space group P4/mbm) in which the Ho atoms occupy three different sites. The neutron diffraction measurements indicate antiferromagnetic order with the Néel temperature T_{N}=7 K. Below T_{N} an additional phase transition at 4.5 K connected with the change of the magnetic structure is observed. The Ho moments in 4(h) site form collinear order up to T_{N} while moments at 2(a) site form sine modulated structure. Determined experimentally magnetic structures are compared to the results of symmetry analysis.
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X-ray diffraction and magnetic measurements of Ho_{5}Ni_{2}In_{4} are reported. This compound crystallizes in the orthorhombic Lu_{5}Ni_{2}In_{4}-type structure. Magnetic data indicate ferromagnetic properties below T_c = 30 K.
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The results of new magnetic dc and neutron diffraction measurements of DyCoSi_2 compound are presented. Below T_{N} equal to 10.9 K the Dy moments form collinear G-type structure with the moment parallel to the c-axis. The value of Dy-moment equal to 5.5(2) μ_{B} are smaller than free Dy^{3+} ion value (10.0 μ_{B}). These and the three-step magnetization process indicate the strong influence of the crystal electric field on the stability of the magnetic order. Increase of the values of the lattice parameters at 1.5 K in reference of these at 20 K indicate magnetostriction effect at low temperatures.
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Magnetic and neutron diffraction data for Tb_{11}O_{20} compound are reported. This compound crystallizes in a triclinic crystal structure described by the space group P1 and is antiferromagnetic with the Néel temperature 5.1 K.
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The neutron powder diffraction (NPD) measurements of the nano-size DyMnO_3 manganite have been performed. The obtained results indicate that this compound crystallizes in the orthorhombic crystal structure described by the space group Pnma. The Mn and Dy moments order antiferromagnetically at different temperatures and form modulated magnetic structure described by the propagation vector k=(k_x, 0, 0) with the different values of k_x component for the Mn and Dy sublattices. The values of k_x component for Mn sublattice increase with decreasing of the temperature and are smaller that in bulk compound. The wide Bragg peaks related to the Dy sublattice suggest that the magnetic order in this sublattice has the cluster-like character.
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The magnetic ordering in ErFe_{0.3}Ge_{2} and ErNi_{0.65}Ge_{2} compounds crystallizing in the orthorhombic structure of the CeNiSi_{2}-type has been investigated by neutron diffraction and magnetic measurements. The Er magnetic moments have been found to order antiferromagnetically below 2.5 K in ErFe_{0.3}Ge_{2} and 2.3 K in ErNi_{0.65}Ge_{2}. The magnetic structure of the former compound can be described by the propagation vector k = (0.044(1), 0, 0.384(1)). The Er magnetic moments are aligned along the a-axis and alternate with the sequence ++- in the unit cell. At 1.5 K they are equal to 5.9(1) μ_{B}. In contrast, the magnetic unit cell of ErNi_{0.65}Ge_{2} has been established to be equal to the chemical one. The magnetic moments in this compound are arranged in a collinear manner pointing along the a-axis with the sequence +-+-. The Er moment value measured at 1.5 K is 2.90(8) μ_{B}.
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The magnetic ordering of the Tb_2Ni_{1.78}In and Tb_2Ni_2In have been studied by neutron diffraction measurements. Tb_2Ni_{1.78}In with the tetragonal Mo_2FeB_2-type (space group P4/mbm, tP10) is antiferromagnet with the Néel temperature equal to 20 K. Below this temperature Tb moments form collinear magnetic structure commensurate with the crystal, described by the propagation vectors equal to (1/4, 1/4, 1/2). Magnetic moment equal to 7.60(6) μ_{B} is parallel to c-axis. The Tb_2Ni_2In in the orthorhombic Mn_2 lB_2-type (space group Cmmm, oC10) was detected as an impurity in the studied sample. It orders antiferromagnetically below ≈ 100 K with collinear moment arrangement described by the propagation vector (1/2, 1/2, 1/2). t 1.6 K μ_{Tb} = 6.33(14) μ_{B} and is parallel to the c-axis.
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Magnetic properties, including magnetic structure, of some RTIn compounds (R = Tb-Er; T = Cu, Ni, Pd, Pt, Au) with the hexagonal ZrNiAl-type crystal structure are reported. Distribution of the rare earth atoms in the basal plane is similar to the kagomé-lattice. Magnetic moments are localized exclusively on the rare earth atoms and form different types of magnetic ordering. Experimental results are analyzed within the Ruderman-Kittel-Kasuya-Yosida and crystal electric field frames. Monte Carlo simulations, including the J_{1} and J_{2} exchange integrals between nearest and next nearest spins and Dzialoshinsky-Moriya interaction, were performed resulting in a number of magnetic phases, some of which are in good agreement with the magnetic ordering determined in the neutron diffraction experiments.
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