Low temperature magnetic and structural behavior of the extended Kagome system YBaCo4O7 has been studied by single crystal neutron diffraction and high-resolution powder X-ray diffraction. Long-range magnetic ordering associated with a structural transition from orthorhombic Pbn2_1 to monoclinic P2_1 symmetry has been found at T_1 ~ 100 K. The interplay between the structural and magnetic degrees of freedom testifies that the degeneracy of the magnetic ground state, present in the orthorhombic phase, is lifted through a strong magnetoelastic coupling, as observed in other frustrated systems. At T_2 ~ 60 K, an additional magnetic transition is observed, though iso-symmetric. Models for the magnetic structures below T_1 and T_2 are presented, based on refinements using a large number of independent reflections. The results obtained are compared with previous single crystal and powder diffraction studies on this and related compositions.
@article{arxiv.1007.4683,
title = {Spin-ordering and magnetoelastic coupling in the extended Kagome system YBaCo4O7},
author = {D. D. Khalyavin and P. Manuel and B. Ouladdiaf and A. Huq and H. Zheng and J. F. Mitchell and L. C. Chapon},
journal= {arXiv preprint arXiv:1007.4683},
year = {2015}
}