Two-Dimensional XY Model with the Account of Magnetoelastic Coupling

Phase Transition in Temperature ?Quadrupolar Phase-Disordered Phase? in a Two-Dimensional Non-Heisenberg Ferromagnet

“…Let us investigate the spectra of elementary excitations in quadrupolar phase. We use the method of bosonization of the Hubbard operators [10,11]. We associate the operators X a n with the pseudo-Hubbard operatorsX X a n , which are related to the Bose creation and annihilation operators for magnons as follows: X X 10 n ¼ ð1 À a þ n a n À b þ n b n Þ a n ;X X 01 n ¼ a þ n ;X X 1À1 n ¼ ð1 À a þ n a n À b þ n b n Þ b n ;…”

Influence of Dipole Interaction on the Phase Transitions Due to Temperature Variation in Two-Dimensional Ferromagnets

“…It is somewhat convenient to use the Hubbard operators [17][18][19][20]. Separating the mean field out of the exchange part of the Hamiltonian (11), the single-site Hamiltonian is obtained as…”

“…The denominator of the Green function determines the dispersion equation of coupled ME waves [10,[18][19][20] det kd ij þ x ij k ¼ 0 ; …”

Spin waves in a semi‐infinite XY ferromagnet

“…Some real systems such as BaNi 2 (PO 4 ) 2 or Rb 2 CrCl 4 can be regarded as three-dimensional XY ferromagnets with very large intralayer to interlayer coupling ratio [16]. The XY model is used for a description of stratified magnets such as K 2 CuF 4 [17]. Since the XY model has different magnetic properties in comparison with the Heisenberg one [17], one can expect that SSW near the surface of an XY ferromagnet differ from those in the Heisenberg model.…”

“…The XY model is used for a description of stratified magnets such as K 2 CuF 4 [17]. Since the XY model has different magnetic properties in comparison with the Heisenberg one [17], one can expect that SSW near the surface of an XY ferromagnet differ from those in the Heisenberg model. However, we are not aware of work devoted to this question.…”