Prokes, K.; Mydosh, J.A.; Prokhnenko, O.; Stein, W.-D.; Landsgesell, S.; Hermes, W.; Feyerherm, R.; Pöttgen, R.: Antiferromagnetic ordering in a mixed-valent cerium compound CeRuSn. Physical Review B 87 (2013), p. 094421/1-9
10.1103/PhysRevB.87.094421
Abstract:
We report the results of extensive neutron powder diffraction experiments on a ternary compound CeRuSn in a temperature range from 2 to 520 K. At room temperature CeRuSn orders in a monoclinic structure that is related to the CeCoAl type by the doubling of the c-axis parameter caused by the splitting of the original single sites for each element into two sites. Upon cooling a very broad hysteretic structural transition has been observed in CeRuSn leading to the presence of higher-ordered variants having multiple c-axis parameters. Depending on the temperatures, one or the other variant seems to be more stable, but the sample as a whole becomes multiphase. We find also evidence for further symmetry lowering at low temperatures. CeRuSn is found to exhibit an antiferromagnetic order below T-N = 2.8(1) K. The order is described by two incommensurate propagation vectors q(1) = (0,0, approximate to 0.30) and q(2) = (0,0, approximate to 0.43) with respect to the doubled crystal structure variant. Although the details of themagnetic structure remain elusive, the best agreement has been found for a complicated distorted cycloidal magnetic structure with Ce moments of approximate to 0.7 mu(B) being confined to the ac plane.