Magnetic and structural study of La(1.8)Sr(0.2)NiO(4)
Neutron-diffraction experiments with both polarised and unpolarised neutrons have been performed on single crystals of (La(1.8)Sr(0.2))NiO(4). The material is tetragonal at room temperature but distorts to the orthorhombic (Bmab) modification at 120+/-5 K with a second-order phase transition. The structural parameters are similar to those in the pure La(2)NiO(4). The susceptibility is highly anisotropic at low temperature with X(ab) (field applied perpendicular to the long axis) showing a peak at approximately 17 K. However, there is no evidence for long-range magnetic order. Polarised neutron-diffraction was used to measure the induced magnetisation density in a field of 4.6 T and at 20 K. The results can be understood by using a slightly expanded Ni(2+) form factor and invoking a small positive susceptibility at the La site. There is also evidence for covalency between the Ni and O(2) atoms along the c axis. The total moment, as determined by these neutron experiments, is in good agreement with that determined by magnetisation experiments.
Bibliographic Reference: Article: Physical Review B, Vol. 43 (1990) No. 1, pp. 448-456
Record Number: 199110312 / Last updated on: 1994-12-02
Original language: en
Available languages: en