Quantum Selection of Order in an X X Z Antiferromagnet on a Kagome Lattice
Résumé
Selection of the ground state of the kagome-lattice XXZ antiferromagnet by quantum fluctuations is investigated by combining nonlinear spin-wave and real-space perturbation theories. The two methods unanimously favor q = 0 over root 3 x root 3 magnetic order in a wide range of the anisotropy parameter 0 <= Delta less than or similar to 0.72. Both approaches are also in accord on the magnitude of the quantum order-by-disorder effect generated by topologically nontrivial, looplike spin-flip processes. A tentative S-Delta phase diagram of the model is proposed.