Finite-temperature order-disorder phase transition in a frustrated bilayer quantum Heisenberg antiferromagnet in strong magnetic fields
Finite-temperature order-disorder phase transition in a frustrated bilayer quantum Heisenberg antiferromagnet in strong magnetic fields
复制标题
强磁场中受抑双层量子海森堡反铁磁体的有限温度有序-无序相变
DOI：
10.1103/physrevb.74.144430
复制
发表时间：
2006
影响因子：
3.7
通讯作者：
T. Krokhmalskii
中科院分区：
文献类型：
--
作者：
J. Richter;O. Derzhko;T. Krokhmalskii
我们研究了受抑双层量子海森堡反铁磁体在饱和磁场附近的低温下的热力学性质。自旋模型的低能自由度被映射到方形晶格上的硬方形气体上。我们使用有限自旋系统的精确对角化数据来检查这种描述的有效性。使用经典的蒙特卡罗方法，我们定量描述了饱和场周围低温下自旋模型的热力学。所考虑的二维海森堡反铁磁体的主要特性与方晶格上的硬方模型的相变有关，属于二维伊辛模型普适性类别。它表现为在刚好低于饱和场的磁场中观察到的自旋系统比热的对数（低）温度奇点。
We investigate the thermodynamic properties of the frustrated bilayer quantum Heisenberg antiferromagnet at low temperatures in the vicinity of the saturation magnetic field. The low-energy degrees of freedom of the spin model are mapped onto a hard-square gas on a square lattice. We use exact diagonalization data for finite spin systems to check the validity of such a description. Using a classical Monte Carlo method we give a quantitative description of the thermodynamics of the spin model at low temperatures around the saturation field. The main peculiarity of the considered two-dimensional Heisenberg antiferromagnet is related to a phase transition of the hard-square model on the square lattice, which belongs to the two-dimensional Ising model universality class. It manifests itself in a logarithmic (low-)temperature singularity of the specific heat of the spin system observed for magnetic fields just below the saturation field.