装饰正方形（利布）晶格上混合自旋伊辛模型中的热相变：非零磁场下的精确结果
Thermal phase transitions in a mixed-spin Ising model on the Lieb lattice: Exact results beyond zero magnetic field
AI总结：
研究装饰正方形晶格上混合自旋伊辛模型，用广义装饰-迭代变换将其映射到有效自旋-1/2伊辛模型，在有效场消失时完全可解，揭示了三个基态相及多种相变，精确分析预测经蒙特卡罗模拟验证。
AI中文摘要：
我们研究了包含单轴单离子各向异性和磁场的装饰正方形（利布）晶格上自旋-1/2与自旋-1混合伊辛模型的基态和有限温度性质。通过广义装饰-迭代变换，该模型被精确映射到具有有效最近邻相互作用和有效场的正方形晶格上的有效自旋-½伊辛模型。只要有效场消失，即使对于有限值的外加磁场，所研究的模型也变得完全可解。基态分析揭示了三个不同相：亚铁磁相（FRI）、无序相（DP）和铁磁相（FM）。FRI和DP相之间的基态边界产生了一个不连续热相变的圆顶形表面，该表面由与连续热相变相关的伊辛型临界点线终止。连续和不连续热相变都属于由有效场消失定义的完全可解参数范围，尽管外加磁场是有限的。在一个狭窄参数区域内识别出两个连续的不连续热诱导重入相变DP-FRI-DP。包括重入、场驱动和热驱动相变在内的精确分析预测通过经典蒙特卡罗模拟得到独立验证。
英文摘要：
We investigate the ground-state and finite-temperature properties of a mixed spin-1/2 and spin-1 Ising model on a decorated square (Lieb) lattice incorporating a uniaxial single-ion anisotropy and magnetic field. By employing the generalized decoration-iteration transformation, the model is mapped exactly onto an effective spin-1/2 Ising model on the square lattice characterized by an effective nearest-neighbor interaction and an effective field. The studied model consequently becomes exactly solvable even for finite values of the applied magnetic field whenever the effective field vanishes. The ground-state analysis reveals three distinct phases: ferrimagnetic phase (FRI), disordered phase (DP), and ferromagnetic (FM) phase. The ground-state boundary between FRI and DP phases gives rise to a dome-shaped surface of discontinuous thermal phase transitions, which is terminated by a line of Ising-type critical points associated with continuous thermal phase transitions. Both continuous and discontinuous thermal phase transitions belong to the exactly solvable parameter regime defined by a vanishing effective field in spite of the fact that the applied magnetic field is finite. Two consecutive discontinuous thermally-induced reentrant phase transitions DP-FRI-DP are identified in a narrow parameter region. The exact analytical predictions including reentrance, field- and thermally-driven phase transitions are independently verified by classical Monte Carlo simulations.
