Li Peng, Su Haibin, Dong Hui-Ning, Shen Shun-Qing
Department of Physics, Sichuan University, Chengdu 610064, People's Republic of China.
J Phys Condens Matter. 2009 Aug 12;21(32):326005. doi: 10.1088/0953-8984/21/32/326005. Epub 2009 Jul 20.
We study a triangular frustrated antiferromagnetic Heisenberg model with nearest-neighbor interactions J(1) and third-nearest-neighbor interactions J(3) by means of Schwinger-boson mean-field theory. By setting an antiferromagnetic J(3) and varying J(1) from positive to negative values, we disclose the low-temperature features of its interesting incommensurate phase. The gapless dispersion of quasiparticles leads to the intrinsic T(2) law of specific heat. The magnetic susceptibility is linear in temperature. The local magnetization is significantly reduced by quantum fluctuations. We address possible relevance of these results to the low-temperature properties of NiGa(2)S(4). From a careful analysis of the incommensurate spin wavevector, the interaction parameters are estimated as J(1)≈-3.8755 K and J(3)≈14.0628 K, in order to account for the experimental data.
我们借助施温格玻色子平均场理论研究了一个具有最近邻相互作用(J(1))和第三近邻相互作用(J(3))的三角受挫反铁磁海森堡模型。通过设定反铁磁的(J(3))并将(J(1))从正值变化到负值，我们揭示了其有趣的非公度相的低温特征。准粒子的无隙色散导致了比热的固有(T(2))定律。磁化率在温度上呈线性关系。量子涨落显著降低了局域磁化强度。我们讨论了这些结果与(NiGa(2)S(4))低温性质的可能相关性。通过对非公度自旋波矢的仔细分析，为了符合实验数据，估计相互作用参数为(J(1)≈ -3.8755 K)和(J(3)≈ 14.0628 K)。
