Thermodynamic properties of an S=12 ring-exchange model on the triangular lattice
Thermodynamic properties of an S=12 ring-exchange model on the triangular lattice
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DOI：
10.1103/physrevb.101.235115
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发表时间：
2019-12
影响因子：
3.7
通讯作者：
K. Seki;S. Yunoki
中科院分区：
文献类型：
--
作者：
K. Seki;S. Yunoki
利用数值精确对角化技术和有限温度Lanczos方法的块扩展形式，研究了三角晶格上具有反铁磁近邻相互作用和四自旋环交换相互作用的$S=1/2$Heisenberg模型的热力学性质.在周期边界条件下对小团簇进行了计算。与纯三角形情形的${J}_{mathm{c}}=0$不同，比热呈现出${J}_{\mathm{c}}/J\ensuremathm{\gtrsim}0.04$的特征双峰结构。由熵和均匀磁化率的计算结果表明，对于${J}{\mathm{c}}/J\ensureath{\gtrsim}0.04$，在磁激发下存在非磁激发。
By using a numerically exact diagonalization technique and a block-extended version of the finite-temperature Lanczos method, we study thermodynamic properties of an $S=1/2$ Heisenberg model on the triangular lattice with an antiferromagnetic nearest-neighbor interaction $J$ and a four-spin ring-exchange interaction ${J}_{\mathrm{c}}$. Calculations are performed on small clusters under the periodic-boundary conditions. In contrast to the purely triangular case with ${J}_{\mathrm{c}}=0$, the specific heat exhibits a characteristic double-peak structure for ${J}_{\mathrm{c}}/J\ensuremath{\gtrsim}0.04$. From the calculations of the entropy and the uniform magnetic susceptibility, it is shown that nonmagnetic excitations exist below the magnetic excitation for ${J}_{\mathrm{c}}/J\ensuremath{\gtrsim}0.04$.