Ordering in two-dimensional Ising models with competing interactions

• Veröffentlicht in: Физика низких температур
• Datum: 2005
• Hauptverfasser: Chitov, G.Y., Gros, C.
• Format: Artikel
• Sprache: Englisch
• Veröffentlicht: Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України 2005
• Schlagworte: К семидесятилетию антиферромагнетизма
• Online Zugang: https://nasplib.isofts.kiev.ua/handle/123456789/121690
• Назва журналу: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Zitieren: Ordering in two-dimensional Ising models with competing
 interactions / G.Y. Chitov, C. Gros // Физика низких температур. — 2005. — Т. 31, № 8-9. — С. 952-967. — Бібліогр.: 33 назв. — англ.

We study the 2D Ising model on a square lattice with additional non-equal diagonal next-nearest
 neighbor interactions. The cases of classical and quantum (transverse) models are considered.
 Possible phases and their locations in the space of three Ising couplings are analyzed. In particular,
 incommensurate phases occurring only at non-equal diagonal couplings, are predicted. We also analyze
 a spin-pseudospin model comprised of the quantum Ising model coupled to XY spin chains in
 a particular region of interactions, corresponding to the Ising sector’s super-antiferromagnetic
 (SAF) ground state. The spin-SAF transition in the coupled Ising-XY model into a phase with
 co-existent SAF Ising (pseudospin) long-range order and a spin gap is considered. Along with destruction
 of the quantum critical point of the Ising sector, the phase diagram of the Ising-XY
 model can also demonstrate a re-entrance of the spin-SAF phase. A detailed study of the latter is
 presented. The mechanism of the re-entrance, due to interplay of interactions in the coupled
 model, and the conditions of its appearance are established. Applications of the spin-SAF theory
 for the transition in the quarter-filled ladder compound NaV₂O₅ are discussed.