Abstract

Ground state properties of the spin − 1∕2 Falicov-Kimball model on a triangular lattice in the presence of uniform external magnetic field are explored. Both the orbital and the Zeeman field-induced effects are taken into account and in each unit cell only rational flux fractions are considered. Numerical results, obtained with the help of Monte Carlo simulation algorithm, reveal that the ground state properties strongly depend on the onsite Coulomb correlation between itinerant and localized electrons, orbital magnetic field as well as the Zeeman splitting. Strikingly, for the on-site Coulomb correlation U∕t ≈ 1, the Zeeman splitting produces a phase transition from paramagnetic metal/insulator to ferromagnetic insulator/metal transition in the itinerant electron subsystem accompanied by the phase segregation to the regular/quasi-regular phase in the localized electrons subsystem. For the onsite Coulomb correlation U∕t ≈ 5, although no metal to insulator transition is observed but a magnetic phase transition from paramagnetic phase to ferromagnetic phase in the itinerant electron subsystem is observed with the Zeeman splitting. These results are applicable to the layered systems e.g. cobaltates, rare earth and transition metal dichalcogenides, GdI₂, NaTiO₂, NaV O₂ and Be_xZn_1−xO etc. It has been also proposed that the results can be realized in the optical lattices with mixtures of light atoms and heavy atoms using the ultra-cold atomic techniques.

Graphical abstract

中文翻译：

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自旋1∕2 Falicov-Kimball模型在带有外部磁场的三角形晶格上的金属-绝缘体跃迁和带磁

摘要

研究了在均匀外部磁场存在下自旋−1∕2 Falicov-Kimball模型在三角形晶格上的基态性质。轨道效应和塞曼效应都被考虑在内，并且在每个晶胞中仅考虑了合理的通量分数。借助蒙特卡罗模拟算法获得的数值结果表明，基态特性强烈依赖于流动剂和局部电子之间的库仑相关性，轨道磁场以及塞曼分裂。引人注目的是，对于现场库仑相关ù /吨≈1，塞曼分裂在巡回电子子系统中产生从顺磁性金属/绝缘体到铁磁绝缘体/金属的相变，并伴随相分离到局部电子子系统中的规则/准规则相。对于现场库仑相关ü /吨≈5，虽然没有金属到绝缘体转变观察但是从顺磁相到铁磁相的磁相变的巡游电子子系统与塞曼分裂观察。这些结果适用于层状体系，例如钴酸盐，稀土和过渡金属_二卤化物，GdI ₂，NaTiO ₂，NaV O ₂和Be _x Zn _{1- x} O等。还提出了使用超冷原子技术在轻，重原子混合的晶格中实现结果的方法。

图形概要