Abstracts 2000

Abstract of Publication No. 368

K. W. Krämer, H. U. Güdel, P. Fischer, F. Fauth, M. T. Fernandez-Diaz and T. Hauss
Triangular antiferromagnetic order in the honeycomb layer lattice of ErCl3
Eur. Phys. J. B 18, 39-47 (2000)      Full Text (PDF)      DOI-Link     

Abstract: ErCl3 crystallizes in the AlCl3-type layer structure. The crystal structure was refined in the paramagnetic state by powder neutron diffraction. The monoclinic lattice parameters at 1.5K are a = 6.8040(3), b = 11.7456(5), c = 6.3187(3) and b = 110.851(3). The space group is C2/m. Short-range, predominantly in-plane, magnetic ordering occurs above 350mK up to several Kelvin. Below TN = 350(5)mK a three-dimensional antiferromagnetic order with a propagation vector of k = (2/3,0,-1/12) sets in. The magnetic structure of ErCl3 was determined by powder and single-crystal neutron diffraction at temperatures down to 45mK. The Er3+ ions are located on two-dimensional honeycomb layers in the a-b plane. There are two antiferromagnetically coupled 120 triangular sublattices which form right- and left-handed helices along the c-axis. The magnetic moments are oriented in the a-b plane and amount to 3.3(1) mB/Er3+ at saturation. From the temperature dependence of the integrated neutron magnetic peak intensity a critical exponent b = 0.23(2) was derived for the magnetic phase transition.

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