论文标题
在巡回电子系统中由现场库仑相互作用引起的铁磁性
Ferrimagnetism Induced by Off-Site Coulomb Interaction in an Itinerant Electron System
论文作者
论文摘要
由$τ$ -Type分子导体（$τ$ -MC）中的弱铁磁（FM）激励，我们使用两种频段扩展的Hubbard模型检查了其机制。应用随机相近似，我们阐明了在现场和现场相互作用的情况下，单位细胞之间的均匀自旋和电荷波动。应用平均场近似值，我们发现每个单位单元格中的有序状态混合（AFM），弱FM和电荷顺序（CO）组件：我们将此状态分类为铁磁性（FIM）。我们揭示了相互作用和相互作用 - 温度空间中的相图。前者表明，异地相互作用诱导纯AFM的FIM，后者表明降低温度稳定FIM。为了阐明这些相的稳定机制，我们专注于有序状态的微观性质，包括带状结构，费米表面和状态的密度。我们发现FIM状态是从AFM，CO和FM的混合特征获得的。因此，FIM的出现需要现场和异地相互作用。然后，我们讨论降低温度的效果，并预测AFM间隙有助于基于AFM的FIM出现。该FIM状态可能与$τ$ -MC中弱FM的观察有关。
Motivated by weak ferromagnetism (FM) in a $τ$-type molecular conductor ($τ$-MC), we examine its mechanism using a two-band extended Hubbard model. Applying the random phase approximation, we elucidate the uniform spin and charge fluctuations between unit cells in the presence of on-site and off-site interactions. Applying the mean-field approximation, we find the ordered state mixing with antiferromagnetism (AFM), weak FM, and charge ordering (CO) components in each unit cell: we classify this state as ferrimagnetism (FIM). We reveal the phase diagrams in the interaction and interaction-temperature spaces. The former shows that the off-site interaction induces FIM from pure AFM and the latter shows that lowering the temperature stabilizes FIM. To clarify the stabilization mechanism of the phases, we focus on the microscopic nature of the ordered states, including the band structure, Fermi surface, and density of states. We find that the FIM state is obtained from mixing features of AFM, CO, and FM; therefore, the emergence of FIM requires both the on-site and off-site interactions. Then, we discuss the effect of lowering the temperature and predict that the AFM gap assists the emergence of FIM based on AFM. This FIM state is possibly related to the observation of the weak FM in $τ$-MC.
