Abstract
Using mean-field theory, exact diagonalizations, and flavor theory, we have precisely mapped out the phase diagram of the bilinear-biquadratic Heisenberg model on the triangular lattice in a magnetic field, with emphasis on the quadrupolar phases and their excitations. In particular, we show that ferroquadrupolar order can coexist with short-range helical magnetic order, and that the antiferroquadrupolar phase is characterized by a remarkable magnetization plateau, in which one site per triangle retains quadrupolar order while the other two are polarized along the field. Implications for actual magnets are discussed.
- Received 9 May 2006
DOI:https://doi.org/10.1103/PhysRevLett.97.087205
©2006 American Physical Society