Fractional topological insulator precursors in spin-orbit fermion ladders
Fractional topological insulator precursors in spin-orbit fermion ladders
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DOI：
10.1103/physrevb.100.235122
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发表时间：
2018-06
影响因子：
3.7
通讯作者：
R. Santos;B. B'eri
中科院分区：
文献类型：
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作者：
R. Santos;B. B'eri
研究了具有自旋-轨道耦合的费米子阶梯中分数阶拓扑绝缘子的前驱态。在微观激发玻色子化方法中，我们研究了在分数有效填充$\nu=1/3$时，依赖于同自旋和自旋间相互作用的不同竞争相。在自旋解耦极限下，我们发现中等范围的强排斥相互作用可能导致具有两个时间反转的准一维劳克林相副本的部分间隙态。该FTI前驱体与显示准远程密度波序的腿间部分间隙相竞争，然而，如果相互作用具有适当的各向异性，或者在腿空间中足够接近SU（$2$）对称，则可以稳定。当FTI相存在时，它对较小的旋间相互作用具有适度的鲁棒性；这些引入了轨道反铁磁性和键密度波特征的竞争性部分间隙相。对FTI前驱体进行强耦合分析，发现自旋间相互作用的主要作用是诱导前驱体FTI边缘模式之间的相关准粒子后向散射。虽然这一过程与拓扑阶段竞争，但我们通过考虑一组阶梯表明，它的影响可能在接近二维情况时消失。考虑到时间反转对称性破缺扰动，我们还描述了一种每半周期绝热泵送$1/6$电荷的协议，从而提供了已经在单阶梯状态中产生的量子化FTI签名。
We study precursor states of fractional topological insulators (FTIs) in interacting fermionic ladders with spin-orbit coupling. Within a microscopically motivated bosonization approach, we investigate different competing phases depending on same-spin and interspin interactions at fractional effective filling $\nu=1/3$ per spin. In the spin-decoupled limit, we find that strong repulsive interactions of already moderate range may lead to a partially gapped state with two time-reversed copies of a quasi-one dimensional Laughlin phase. This FTI precursor competes with an interleg partially gapped phase displaying quasi long-range density wave order, however it may be stabilized if interactions have suitable anisotropy, or are sufficiently near SU($2$) symmetry, in leg space. When the FTI phase is present, it is moderately robust to small interspin interactions; these introduce competing partially gapped phases of orbital antiferromagnetic and bond density wave character. Performing a strong coupling analysis of the FTI precursor regime, we find that the main effect of interspin interactions is to induce correlated quasiparticle backscattering between the precursor FTI edge modes. Although this process competes with the topological phase, we show, by considering an array of ladders, that its influence may disappear upon approaching the two dimensional case. Considering time-reversal symmetry breaking perturbations, we also describe a protocol that adiabatically pumps $1/6$ charge per half-cycle, thus providing a quantized FTI signature arising already in the single ladder regime.