Abstract
Magnetic-susceptibility χ(T) and neutron-diffraction studies on single-crystal specimens of are reported. A three-dimensional antiferromagnetic structure similar to that in is identified below the Néel temperature =251±5 K by neutron diffraction, with an ordered moment μ(10 K)=0.34±0.04 /Cu aligned along the [110] crystal direction. This moment is comparable to those for samples with similar . No structural transition from the tetragonal I4/mmm space group is observed between 10 and 300 K. The χ(T) near is consistent with the tetragonal structure, showing no evidence for the peak at seen in orthorhombic , arising from the Dzyaloshinsky-Moriya interaction, which is absent without the orthorhombic distortion. Above the exchange coupling constant J between adjacent Cu ions is evaluated from χ(T) and found to be essentially identical to that in . The anisotropic Cu spin and Van Vleck susceptibilities are also estimated from the analysis.
- Received 31 August 1989
DOI:https://doi.org/10.1103/PhysRevB.41.1926
©1990 American Physical Society