Two-step magnetic ordering in as-cast and annealed DyNi<sub>2</sub>B<sub>2</sub>C samples
Moshe Kuznietz; Hiroyuki Takeya
Журнал:
Journal of Physics: Condensed Matter
Дата:
1999-08-30
Аннотация:
Polycrystalline DyNi<sub>2</sub>B<sub>2</sub>C samples, as-cast and annealed, were prepared and studied by x-ray diffraction (indicating the LuNi<sub>2</sub>B<sub>2</sub>C-type structure) and by magnetization. The magnetization study (in H = 20 Oe) of both samples indicates initial ordering at T<sub>N</sub> = 16.3(3) K, and a second transition, especially in the annealed one, at T<sub>o</sub> = 10.4(3) K. Transitions into superconducting states occur at T<sub>c</sub>6 K in the annealed sample and at higher T<sub>c</sub> in the as-cast sample. The two magnetic transitions agree with available neutron-diffraction data on annealed polycrystalline DyNi<sub>2</sub><sup>11</sup>B<sub>2</sub>C. A two-step magnetic ordering is proposed, involving initial ferromagnetic order in the basal planes, followed by a build-up of the correct antiferromagnetic (alternate) stacking of these planes throughout the samples. It is completed at the lower transition, T<sub>o</sub>, only in the annealed sample, leading to its lower T<sub>c</sub>.
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