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Tetragonal to triclinic structural transition in the prototypical CeScSi induced by a two-step magnetic ordering: a temperature-dependent neutron diffraction study of CeScSi, CeScGe and LaScSi

TitleTetragonal to triclinic structural transition in the prototypical CeScSi induced by a two-step magnetic ordering: a temperature-dependent neutron diffraction study of CeScSi, CeScGe and LaScSi
Publication TypeJournal Article
Year of Publication2017
AuthorsRitter, C, Provino, A, Manfrinetti, P, Pathak, AK
JournalJournal of Physics-Condensed Matter
Volume29
Pagination045802
Date Published02
Type of ArticleArticle
ISBN Number0953-8984
Accession NumberWOS:000389233600001
Keywordscerium intermetallics, diffraction, magnetic structure, magnetostructural transition, nd, neutron, physics, rare earth ternary compounds
Abstract

sociated with the first ordering is T-N similar to 26 K and T-N similar to 48 K for the silicide and the germanide, respectively. Here the spin directions are rigorously confined to the basal plane, with values of the Ce magnetic moments of mu(Ce) = 0.8-1.0 mu(B). A second magnetic transition, which takes place at slightly lower temperatures, results in a canting of the ordered magnetic moments out of the basal plane which is accompanied by an increase of the magnetic moment value of Ce to mu(Ce) = 1.4-1.5 mu(B). Interestingly, the second magnetic transition leads to a structural distortion in both compounds from the higher-symmetry tetragonal space group I4/mmm to the lower-symmetry and triclinic I-1 (non-standard triclinic). Magnetic symmetry analysis shows that the canted structure would not be allowed in the I4/mmm space group; this result further confirms the structural transition. The transition temperatures TS from I4/mmm to I-1 are about 22 K in CeScSi and 36 K in CeScGe, i.e. well below the temperature of the first onset of antiferromagnetic order observed in this work (or below the ordering temperature, previously reported as either TC or TN). This result, along with the synchronism of the magnetic and structural transitions, suggests a magnetostructural origin of this structural distortion. We have also carried out powder neutron diffraction for LaScSi as a non-magneticallyordering reference compound and compared the results with those of CeScSi and CeScGe compounds.

DOI10.1088/1361-648x/29/4/045802
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Alternate JournalJ. Phys.-Condes. Matter