paper

Neutron powder diffraction study of NaMn $_{2}$ O $_{4}$ and Li $_{0.92}$ Mn $_{2}$ O $_{4}$ : New insights on spin-charge-orbital ordering

arXiv:2006.16660 · doi:10.1103/PhysRevResearch.2.043143

Abstract

The high-pressure synthesized quasi-one-dimensional compounds NaMn $_{2}$ O $_{4}$ and Li $_{0.92}$ Mn $_{2}$ O $_{4}$ are both antiferromagnetic insulators, and here their atomic and magnetic structures were investigated using neutron powder diffraction. The present crystal structural analyses of NaMn2O4 reveal that Mn3+/Mn4+ charge-ordering state exist even at low temperature (down to 1.5 K). It is evident from one of the Mn sites shows a strongly distorted Mn3+ octahedra due to the Jahn-Teller effect. Above TN = 39 K, a two-dimensional short-range correlation is observed, as indicated by an asymmetric diffuse scattering. Below TN, two antiferromagnetic transitions are observed (i) a commensurate long-range Mn3+ spin ordering below 39 K, and (ii) an incommensurate Mn4+ spin ordering below 10 K. The commensurate magnetic structure (kC = 0.5, -0.5, 0.5) follows the magnetic anisotropy of the local easy axes of Mn3+, while the incommensurate one shows a spin-density-wave order with kIC = (0,0,0.216). For Li $_{0.92}$ Mn $_{2}$ O $_{4}$ , on the other hand, absence of a long-range spin ordered state down to 1.5 K is confirmed.

11 pages, 8 figures

Neutron powder diffraction study of NaMn2​O4​ and Li0.92​Mn2​O4​: New insights on spin-charge-orbital ordering

Abstract

Neutron powder diffraction study of NaMn $_{2}$ O $_{4}$ and Li $_{0.92}$ Mn $_{2}$ O $_{4}$ : New insights on spin-charge-orbital ordering