Journal of Magnetism and Magnetic Materials ( IF 2.7 ) Pub Date : 2021-09-03 , DOI: 10.1016/j.jmmm.2021.168441 Konrad Jerzy Kapcia 1
The extended Hubbard model in the atomic limit, which is equivalent to lattice fermionic gas, is considered on the triangular lattice. The model includes onsite Hubbard interaction and both nearest-neighbor () and next-nearest-neighbor () density–density intersite interactions. The variational approach treating the term exactly and the terms in the mean-field approximation is used to investigate thermodynamics of the model and to find its finite temperature () phase diagrams (as a function of particle concentration) for and . Two different types of charge-order (i.e., DCO and TCO phases) within unit cells as well as the nonordered (NO) phase occur on the diagram. Moreover, several kinds of phase-separated (PS) states (NO/DCO, DCO/DCO, DCO/TCO, and TCO/TCO) are found to be stable for fixed concentration. Attractive stabilizes PS states at and it extends the regions of their occurrence at . The evolution of the diagrams with increasing of is investigated. It is found that some of the PS states are stable only at . Two different critical values of are determined for the PS states, in which two ordered phases of the same type (i.e., two domains of the DCO or TCO phase) coexist.
中文翻译:
三角形晶格上的电荷顺序:有限温度下的次近邻吸引力的影响
原子极限下的扩展哈伯德模型,相当于点阵 费米子气体,被考虑在三角晶格上。该模型包括现场哈伯德 交互和最近邻() 和下一个最近的邻居 () 密度-密度点间相互作用。变分方法处理 准确的术语和 平均场近似中的项用于研究模型的热力学并找到其有限温度() 相图(作为粒子浓度的函数) 和 . 两种不同类型的充电顺序(即 DCO 和 TCO 阶段)单元格以及无序 (NO) 相出现在图中。此外,发现几种相分离 (PS) 状态(NO/DCO、DCO/DCO、DCO/TCO 和 TCO/TCO)对于固定浓度是稳定的。吸引人的 将 PS 状态稳定在 并将它们的发生区域扩展到 . 图表随着数量的增加而演变被调查。发现一些 PS 状态仅在. 两个不同的临界值 为 PS 状态确定,其中两个相同类型的有序相(即 DCO 或 TCO 相的两个域)共存。