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Magnetic transitions in the spin-5/2 frustrated magnet BiMn2PO6 and strong lattice softening in BiMn2PO6 and BiZn2PO6 below 200 K

TitleMagnetic transitions in the spin-5/2 frustrated magnet BiMn2PO6 and strong lattice softening in BiMn2PO6 and BiZn2PO6 below 200 K
Publication TypeJournal Article
Year of Publication2014
AuthorsNath, R, Ranjith, KM, Roy, B, Johnston, DC, Furukawa, Y, Tsirlin, AA
JournalPhysical Review B
Volume90
Pagination024431
Date Published07
Type of ArticleArticle
ISBN Number1098-0121
Accession NumberWOS:000339974200002
Keywordsantiferromagnetics, crystal, ladders, mn3o4, nmr, relaxation, state, superconductivity, susceptibility, system
Abstract

CW) similar or equal to -78 K. The. data indicate long-range AFM ordering below T-N similar or equal to 30 K, confirmed by a sharp lambda-shaped peak in C-p(T) at 28.8 K. The magnetic entropy at 100 K extracted from the C-p(T) data is consistent with spin S = 5/2 for the Mn+2 cations. The band-theory calculations indicate that BiMn2PO6 is an AFM compound with dominant interactions J(1)/k(B) similar or equal to 6.7 K and J(3)/k(B) similar or equal to 5.6 K along the legs and rungs of a Mn two-leg spin-ladder, respectively. However, sizable and partially frustrating interladder couplings lead to an anisotropic three-dimensional magnetic behavior with long-range AFM ordering at T-N similar or equal to 30 K observed in the chi, C-p, and NMR measurements. A second magnetic transition at approximate to 10 K is observed from the chi and NMR measurements but is not evident in the C-p data. The C-p data at low T suggest a significant contribution from AFM spin waves moving in three dimensions and the absence of a spin-wave gap. A detailed analysis of the NMR spectra indicates commensurate magnetic order between 10 and 30 K, while below 10 K additional features appear that may arise from an incommensurate modulation and/or spin canting. The commensurate order is consistent with microscopic density functional calculations that yield a collinear Neel-type AFM spin arrangement both within and between the ladders, despite the presence of multiple weak interactions frustrating this magnetic structure of the Mn spins. Frustration for AFM ordering and the one-dimensional spatial anisotropy of the three-dimensional spin interactions are manifested in the frustration ratio f = |theta(CW)|/T-N similar or equal to 2.6, indicating a suppression of T-N from 68 K in the absence of these effects to the observed value of about 30 K in BiMn2PO6.

DOI10.1103/PhysRevB.90.024431
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