Carvalho R C P, Pereira M S S, de Oliveira I N, Strečka J, Lyra M L
Instituto de Física, Universidade Federal de Alagoas 57072-970 Maceió-AL, Brazil.
J Phys Condens Matter. 2017 Sep 13;29(36):365801. doi: 10.1088/1361-648X/aa7d61. Epub 2017 Jul 4.
We introduce an exactly solvable hybrid spin-ladder model containing localized nodal Ising spins and interstitial mobile electrons, which are allowed to perform a quantum-mechanical hopping between the ladder's legs. The quantum-mechanical hopping process induces an antiferromagnetic coupling between the ladder's legs that competes with a direct exchange coupling of the nodal spins. The model is exactly mapped onto the Ising spin ladder with temperature-dependent two- and four-spin interactions, which is subsequently solved using the transfer-matrix technique. We report the ground-state phase diagram and compute the fermionic concurrence to characterize the quantum entanglement between the pair of interstitial mobile electrons. We further provide a detailed analysis of the local spin ordering including the pair and four-spin correlation functions around an elementary plaquette, as well as, the local ordering diagrams. It is shown that a complex sequence of distinct local orderings and frustrated correlations takes place when the model parameters drive the investigated system close to a zero-temperature triple coexistence point.
我们引入了一个精确可解的混合自旋梯子模型，该模型包含局域化的节点伊辛自旋和间隙移动电子，这些电子可以在梯子的腿之间进行量子力学跳跃。量子力学跳跃过程在梯子的腿之间诱导出反铁磁耦合，该耦合与节点自旋的直接交换耦合相互竞争。该模型精确映射到具有温度依赖的两自旋和四自旋相互作用的伊辛自旋梯子上，随后使用转移矩阵技术求解。我们报告了基态相图，并计算了费米子并发度以表征间隙移动电子对之间的量子纠缠。我们进一步对局部自旋排序进行了详细分析，包括围绕一个基本格子的两自旋和四自旋相关函数，以及局部排序图。结果表明，当模型参数将所研究的系统驱动到接近零温度三重共存点时，会出现一系列复杂的不同局部排序和受挫关联。
