$p$ -电子分子固体RbO $_2$中的轨道序、堆垛层错和自旋涨落
Orbital order, stacking defects and spin-fluctuations in the $p$-electron molecular solid RbO$_2$
摘要：
我们研究磁振子和轨道行为的本地化O $_2$反键分子$π^*$轨道使用有效的Kugel-Khomskii哈密顿量来自两个带哈伯德模型的跳跃参数从{ \em从头算}密度泛函计算。带内和带间跳跃之间的显著差异导致自旋波色散和轨道基态之间的强耦合，提供了一种直接的方法，从测量的磁振子色散实验确定轨道基态。不同轨道有序态的近简并导致堆叠缺陷，从而进一步调制自旋涨落谱。轨道域的扩散破坏了长程磁序，从而导致观测到的内尔温度显著降低。
英文摘要：
We examine magnon and orbiton behavior in localized O$_2$ anti-bonding molecular $π^*$ orbitals using an effective Kugel-Khomskii Hamiltonian derived from a two band Hubbard model with hopping parameters taken from {\em ab initio} density functional calculations. The considerable difference between intraband and interband hoppings leads to a strong coupling between the spin wave dispersion and the orbital ground state, providing a straightforward way of experimentally determining the orbital ground state from the measured magnon dispersion. The near degeneracy of different orbital ordered states leads to stacking defects which further modulate spin-fluctuation spectra. Proliferation of orbital domains disrupts long-range magnetic order, thus causing a significant reduction in the observed Néel temperature.
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