Lifting of multiphase degeneracy by quantum fluctuations.

We study the effect of quantum fluctuations on the multiphase point of the Heisenberg model with firstand second-neighbor competing interactions and strong uniaxial spin anisotropy D. By studying the structure of perturbation theory we show that the multiphase degeneracy which exists for S=∞ (i.e., for the axial nextnearest-neighbor Ising model) is lifted and that the effect of quantum fluctuations is to stabilize a sequence of phases of wavelength 4,6,8, . . . . This sequence is probably an infinite one. We also show that quantum fluctuations can mediate an infinite sequence of layering transitions through which an interface can unbind from a wall. Disciplines Physics | Quantum Physics Comments At the time of publication, author A. Brooks Harris was affiliated with Oxford University, Oxford, United Kingdom, and Tel Aviv University, Tel Aviv, Israel. Currently, he is a faculty member in the Physics Department at the University of Pennsylvania. This journal article is available at ScholarlyCommons: http://repository.upenn.edu/physics_papers/348 PHYSICAL REVIE%' 8 VOLUME 52, NUMBER 9 1 SEPTEMBER 1995-I Lifting of multiphase degeneracy by quantum fiuctuations A. B. Harris Theoretical Physics, Ozford University, I Keble Road, Oxford OX1 SNP, United Kingdom and School of Physics and Astronomy, Raymond and Beverly Sackler Faculty of Ezact Sciences, Tel Aviv -University, Tel-Aviv 69978, Isro,el C. Micheletti and J. M. Yeomans Theoretical Physics, Ozford University, 1 Keble Road, Ozford OX1 9NP, United Kingdom (Received 6 April 1995) We study the eKect of quantum Buctuations on the multiphase point of the Heisenberg model with firstand second-neighbor competing interactions and strong uniaxial spin anisotropy D. By studying the structure of perturbation theory we show that the multiphase degeneracy which exists for S = oo (i.e., for the axial next-nearest-neighbor Ising model) is lifted and that the eKect of quantum Quctuations is to stabilize a sequence of phases of wavelength 4,6,8,. . . . This sequence is probably an infinite one. We also show that quantum Huctuations can mediate an infinite sequence of layering transitions through which an interface can unbind from a wall.