论文标题
债券订购和分子旋转轨道波动中的集群莫特绝缘子Gata $ _4 $ SE $ _8 $
Bond Ordering and Molecular Spin-Orbital Fluctuations in the Cluster Mott Insulator GaTa$_4$Se$_8$
论文作者
论文摘要
对于自旋轨道耦合与电子相关性竞争的材料，空间各向异性自旋 - 轨道波触点可以稳定变质状态，从而导致物质的许多量子阶段。在这里，我们找到了t $^*$ = 50 k订购式旋转式订单订购过渡之前的动态旋转轨道状态的证据。以上T $^*$，gata $ _4 $ se $ _8 $具有平均立方晶体结构，但总散射测量表明，所有测量温度的ta $ _4 $四面体簇的本地非立方体扭曲$ 2 <t <t <t <t <300 $ k。 $ j \！= \！3/2 $分子轨道职业以及集群ta-se债券。 t $^*$处的自旋轨道订购不能归因于经典的Jahn-Teller机制，并且根据我们的发现，我们提出，群间交互作用以T $^*$的规模作用，以破坏全球对称性。产生的交错群间二聚化模式将单位电池加倍，反映了旋转轨道价键基态。
For materials where spin-orbit coupling is competitive with electronic correlations, the spatially anisotropic spin-orbital wavefunctions can stabilize degenerate states that lead to many and diverse quantum phases of matter. Here, we find evidence for a dynamical spin-orbital state preceding a T$^*$=50 K order-disorder spin-orbital ordering transition in the $j\!=\!3/2$ lacunar spinel GaTa$_4$Se$_8$. Above T$^*$, GaTa$_4$Se$_8$ has an average cubic crystal structure, but total scattering measurements indicate local non-cubic distortions of Ta$_4$ tetrahedral clusters for all measured temperatures $2 < T < 300$ K. Inelastic neutron scattering measurements reveal the dynamic nature of these local distortions through symmetry forbidden optical phonon modes that modulate $j\!=\!3/2$ molecular orbital occupation as well as intercluster Ta-Se bonds. Spin-orbital ordering at T$^*$ cannot be attributed to a classic Jahn-Teller mechanism and based on our findings, we propose that intercluster interactions acting on the scale of T$^*$ act to break global symmetry. The resulting staggered intercluster dimerization pattern doubles the unit cell, reflecting a spin-orbital valence bond ground state.
