Abstract The mixed spin-1/2 and spin-S Ising model on a decorated planar lattice accounting for lattice vibrations of decorating atoms is treated by making use of the canonical coordinate transformation, the decoration-iteration transformation, and the harmonic approximation. It is shown that the magnetoelastic coupling gives rise to an effective single-ion anisotropy and three-site four-spin interaction, which are responsible for the anomalous spin frustration of the decorating spins in virtue of a competition with the equilibrium nearest-neighbor exchange interaction between the nodal and decorating spins. The ground-state and finite-temperature phase diagrams are constructed for the particular case of the mixed spin-1/2 and spin-1 Ising model on a decorated square lattice for which thermal dependencies of the spontaneous magnetization and specific heat are also examined in detail. It is evidenced that a sufficiently strong magnetoelastic coupling leads to a peculiar coexistence of the antiferromagnetic long-range order of the nodal spins with the disorder of the decorating spins within the frustrated antiferromagnetic phase, which may also exhibit double reentrant phase transitions. The investigated model displays a variety of temperature dependencies of the total specific heat, which may involve in its magnetic part one or two logarithmic divergences apart from one or two additional round maxima superimposed on a standard thermal dependence of the lattice part of the specific heat.

中文翻译：

---

在装饰平面晶格上的混合自旋 Ising 模型中由磁弹性耦合强制执行的异常自旋受阻

摘要 利用正则坐标变换、装饰迭代变换和调和近似处理了考虑装饰原子晶格振动的装饰平面晶格上的混合自旋1/2和自旋S Ising模型。结果表明，磁弹性耦合产生了有效的单离子各向异性和三点四自旋相互作用，这是由于与平衡最近邻交换相互作用的竞争而导致装饰自旋的异常自旋受挫的原因在节点和装饰旋转之间。针对混合自旋 1/2 和自旋 1 Ising 模型在装饰方形晶格上的特殊情况构建了基态和有限温度相图，自发磁化强度和比热的热相关性也在细节。有证据表明，足够强的磁弹性耦合导致节点自旋的反铁磁长程有序与受挫反铁磁相内装饰自旋的无序的特殊共存，这也可能表现出双重入相变。研究的模型显示了总比热的各种温度依赖性，