Neutron powder diffraction study of NaMn2O4 and Li0.92Mn2O4: Insights on spin-charge-orbital ordering
Journal article, 2020
High-pressure synthesized quasi-one-dimensional NaMn2O4 and Li0.92Mn2O4 are both antiferromagnetic insulators. Here their atomic and magnetic structures are investigated using neutron powder diffraction. The present crystal structural analyses of NaMn2O4 reveal that a Mn3+/Mn4+ charge-ordering state exists even at low temperature (down to 1.5 K). It is evident that one of the Mn sites shows a strongly distorted Mn3+ octahedron due to the Jahn-Teller effect. Above T-N = 35 K, a two-dimensional short-range correlation is observed, as indicated by asymmetric diffuse scattering. Below T-N, two antiferromagnetic transitions are observed: (i) a commensurate long-range Mn3+ spin ordering below T-N1 = 35 K and (ii) an incommensurate Mn4+ spin ordering below T-N2 = 11 K. Surprisingly, the two antiferromagnetic orders are found to be independent of each other. The commensurate magnetic structure (k(C) = 0.5, 0.5, 0.5) follows the magnetic anisotropy of the local easy axes of Mn3+, while the incommensurate Mn4+ one shows a spin-density-wave or a cycloidal order with k(IC) = (0, 0, 0.216). For Li0.92Mn2O4, on the other hand, the absence of a long-range spin-ordered state is confirmed down to 1.5 K.
Author
N. Matsubara
Royal Institute of Technology (KTH)
E. Nocerino
Royal Institute of Technology (KTH)
K. Kamazawa
Comprehensive Research Organization for Science and Society (CROSS)
O. K. Forslund
Royal Institute of Technology (KTH)
Yasmine Sassa
Chalmers, Physics, Materials Physics
L. Keller
Paul Scherrer Institut
V. V. Sikolenko
Joint Institute for Nuclear Research (JINR)
Karlsruhe Institute of Technology (KIT)
V Pomjakushin
Paul Scherrer Institut
H. Sakurai
National Institute for Materials Science (NIMS)
Jun Sugiyama
Comprehensive Research Organization for Science and Society (CROSS)
M. Mansson
Royal Institute of Technology (KTH)
Physical Review Research
26431564 (ISSN)
Vol. 2 4 043143Subject Categories
Inorganic Chemistry
Other Physics Topics
Condensed Matter Physics
DOI
10.1103/PhysRevResearch.2.043143