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Magnetic Properties of the Spin-1 Two-Dimensional J_{1}-J_{3} Heisenberg Model on a Triangular Lattice

100%

Rubin P., Sherman A., Schreiber M.

vol. 126

issue 1

242-243

Motivated by the recent experiment in NiGa_{2}S_{4}, the spin-1 Heisenberg model on a triangular lattice with the ferromagnetic nearest- and antiferromagnetic third-nearest-neighbor exchange interactions, J_{1} = -(1 - p)J and J_{3} = pJ, J > 0, is studied in the range of the parameter 0 ≤ p ≤ 1. Mori's projection operator technique is used as a method, which retains the rotation symmetry of spin components and does not anticipate any magnetic ordering. For zero temperature several phase transitions are observed. At p ≈ 0.2 the ground state is transformed from the ferromagnetic order into a disordered state, which in its turn is changed to an antiferromagnetic long-range ordered state with the incommensurate ordering vector Q' ≈ (1.16, 0) at p ≈0.31. With growing p the ordering vector moves along the line Q'-Q_{c} to the commensurate point Q_{c} = (2π/3, 0), which is reached at p = 1. The final state with the antiferromagnetic long-range order can be conceived as four interpenetrating sublattices with the 120° spin structure on each of them. Obtained results offer a satisfactory explanation for the experimental data in NiGa_{2}S_{4}.

On the Effects of the Interaction Potential Parameters on Bose-Einstein Condensation

80%

Al-Sugheir M., Al-Khzon H., Al-Maghrabi M., Alna'washi G.

Acta Physica Polonica A

2012

vol. 122

issue 4

704-708

In this work the effect of the potential parameters on the condensate fraction and the critical temperature of neutral many-bosonic system are investigated. A many-body technique called the static fluctuation approximation is used in this study. The interaction potential is modeled by two linear terms. The condensation fraction and critical temperature were found to decrease with increasing the strength or the range of the repulsive part of the potential. On the other hand, the condensation fraction and critical temperature increase with increasing the depth or range of the attractive part of the potential.

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2 Acta Physica Polonica A

1 2014

1 2012

1 Al-Khzon H.

1 Al-Maghrabi M.

1 Al-Sugheir M.

1 Alna'washi G.

1 Rubin P.

1 Schreiber M.

1 Sherman A.

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Magnetic Properties of the Spin-1 Two-Dimensional J_{1}-J_{3} Heisenberg Model on a Triangular Lattice

On the Effects of the Interaction Potential Parameters on Bose-Einstein Condensation