Annihilation of antiferromagnetic order in LiCoO₂ by excess Li

Jun Sugiyama (1) , Yutaka Ikedo (1) , Hiroshi Nozaki (1) , Kazuhiko Mukai (1) , Daniel Andreica (2) , Alex Amato (3) , Michel Ménétrier (4) , Dany Carlier-Larregaray (4) , Claude Delmas (4)

1 Central Research and Development Laboratory
2 Faculty of Physics
3 PSI - Paul Scherrer Institute
4 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux

In order to elucidate the origin of antiferromagnetic (AF) order below 30 K in LiCoO2, in which all the Co3+ ions are in a low-spin state with S=0, the magnetic nature of the Li-excess sample Li1.04Co0.96O1.96 was studied by muon-spin spectroscopy in the temperature range between 1.8 and 100 K. Although disordered localized moments appeared below 25 K, static AF order was not detected even at 1.8 K. Moreover, a small amount of excess Li ions (4%) and oxygen vacancies (2%) was found to change not, vert, similar50% of the sample into a magnetically disordered phase at 1.8 K. The stoichiometric LiCoO2, which was prepared from the same starting materials to those for the Li-excess sample, showed an AF transition at 30 K, while the volume fraction of the AF phase was 10% even at 1.8 K. This therefore excludes the possible role of the excess Li+ on the formation of static AF order.

Mots clés: Antiferromagnetic order; LiCoO₂; Triangular lattice; Oxygen vacancies

Domaines: Matériaux

Jun Sugiyama, Yutaka Ikedo, Hiroshi Nozaki, Kazuhiko Mukai, Daniel Andreica, et al.. Annihilation of antiferromagnetic order in LiCoO₂ by excess Li. Physica B: Condensed Matter, 2009, 404 (5-7), pp.769-772. ⟨10.1016/j.physb.2008.11.177⟩. ⟨hal-00377760⟩