Orbital degeneracy as a source of frustration in LiNiO2
Abstract
Motivated by the absence of cooperative Jahn-Teller effect and of magnetic ordering in LiNiO2 , a layered oxide with triangular planes, we study a general spin-orbital model on the triangular lattice. A mean-field approach reveals the presence of several singlet phases between the SU(4) symmetric point and a ferromagnetic phase, a conclusion supported by exact diagonalizations of finite clusters. We argue that one of the phases, characterized by a large number of low-lying singlets associated to dimer coverings of the triangular lattice, could explain the properties of LiNiO2 , while a ferro-orbital phase that lies nearby in parameter space leads to a new prediction for the magnetic properties of NaNiO2 .
- Publication:
-
Physical Review B
- Pub Date:
- July 2004
- DOI:
- 10.1103/PhysRevB.70.014428
- arXiv:
- arXiv:cond-mat/0401122
- Bibcode:
- 2004PhRvB..70a4428V
- Keywords:
-
- 75.10.Jm;
- 75.40.Cx;
- 75.40.Gb;
- Quantized spin models;
- Static properties;
- Dynamic properties;
- Strongly Correlated Electrons
- E-Print:
- 18 pages, 17 figures