On the mean-field theory of magnetic multilayers with bilinear and biquadratic Heisenberg exchange

Lazarev, S.B.; Škrinjar, M. J.; Kapor, D.; Stojanović, S.

doi:10.1016/s0378-4371(97)00549-9

Cited by 10 publications

(4 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…One approach was to use more sophisticated techniques like Green's functions (GF), as done in [6][7][8][9][10][11][12]. Another direction was to study the influence of surfaces on the magnetic structure [13][14][15][16], while several studies were dedicated to the influence of anisotropy [17,18].…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic properties of the Ising and Heisenberg S = 1 ferromagnet with biquadratic exchange and uniaxial anisotropy

Manojlovic

Pantić

Škrinjar

et al. 2006

Physica Status Solidi (b)

View full text Add to dashboard Cite

We study the thermodynamic properties of 1 S = Ising and Heisenberg ferromagnets with both bilinear and biquadratic exchange and/or uniaxial anisotropy of both easy axis/plane character. Using the meanfield (MF) approximation we evaluated the free energy enabling us to study in detail the behavior of the order parameters and the dependence of the critical point on the anisotropy. We show that in the presence of biquadratic interaction, there is a difference in the behavior between the Ising and the Heisenberg model even in the MF approximation, which is not the case for the bilinear interaction. Combining the equations of motion for Green's functions with identities particular to 1 S = , we managed to perform the random phase approximation without the decoupling of the operators at the same site, avoiding the peculiarities of the Callen -Anderson decoupling. This allowed us to improve the phase diagram for the Heisenberg model. The important result is the demonstration of the effect of anisotropy to nonvanishing of the quadrupolar order parameter at the Curie point.

show abstract

Section: Introductionmentioning

confidence: 99%

Thermodynamic properties of the Ising and Heisenberg S = 1 ferromagnet with biquadratic exchange and uniaxial anisotropy

Manojlovic

Pantić

Škrinjar

et al. 2006

Physica Status Solidi (b)

View full text Add to dashboard Cite

show abstract

“…Applying the standard MFA procedure 26 to the rotated Hamiltonian ͑12͒ ͑for aϭ0), from the minimum of the Gibbs' free energy we obtain the expressions for the magnetizations of the layers and additional relation for the reconstruction angle (T 0, l Јϭ͗Ŝ zЈ (l)͘/S, lϭ0,1,2, . .…”

Section: Analysis Of the Results And Concluding Remarksmentioning

confidence: 99%

Influence of the biquadratic interaction to magnetic surface reconstruction

et al. 1999

View full text Add to dashboard Cite

The surface spin ordering is studied in a ferromagnetic crystal where spins interact both by bilinear and biquadratic interaction. The surface spin configuration is unstable with respect to ferromagnetic alignment for certain values of parameters leading to so-called surface magnetic reconstruction. It is shown that biquadratic interaction enhances the reconstruction. The energy of surface excitations is calculated and it is shown to be much lower than the energy of bulk excitations in presence of surface reconstruction, while the surface Goldstone mode appears only in the case of vanishing external field and anisotropy. Mean field calculation is presented for the study of the behavior of surface magnetization.

show abstract

“…(4) and (5) shows that the higher temperature corresponds to the ferromagnetic ordering (s 1 ws 2 ), while the lower one to the antiferromagnetic ordering (s 1 wKs 2 ). Using the reasoning similar to the one applied in [10], one can show that FM ordering corresponds to the lower free energy, so that it is the stable phase and the system possesses a common (same for all the system) Curie temperature T C Z T C 1 . We shall comment Spirin's results [7] in the final Section and we wish to stress that we obtain the same result (unique T C !)…”

Section: Spin 1 Modelmentioning

confidence: 97%