Title: Antiferromagnetic topological insulators in heavy-fermion systems Show Chinese title

Title: 重费米子体系中的反铁磁拓扑绝缘体

Abstract: The cooperation of electronic correlation and spin-orbit coupling can stabilize magnetic topological insulators which host novel quantum phenomena such as the quantum anomalous Hall state also known as Chern insulator (CI). Here, we investigate the existence of magnetic topological insulators with antiferromagnetic (AF) order in heavy-fermion materials. Our analysis relies on the half-filled Kane-Mele-Kondo (KMK) model with the AF Kondo interaction $J_{\rm K}$ coupling the spin of itinerant electrons with a $S=1/2$ localized spin at each lattice site. We consider the N\'eel AF ordering with the local magnetization not only perpendicular ($z$-AF ordering) but also parallel ($xy$-AF ordering) to the honeycomb plane. We show that in the absence of an energy offset between the two sublattices of the honeycomb structure the system is always topologically trivial. There is a transition from the trivial $xy$-AF insulator ($xy$-AFI) to the trivial Kondo insulator (KI) upon increasing $J_{\rm K}$. We unveil that an alternating sublattice potential can lead to the stabilization of the $z$-AFCI and the $z$-AF quantum spin Hall insulator ($z$-AFQSHI). We address the charge excitations in the bulk as well as at the edges of the KMK model. We provide a systematic comparison between the size of the charge gap in the AFCI in heavy-fermion materials and the size of the charge gap in the AFCI in transition-metal compounds. Our findings can guide the future experimental studies searching for AF topological insulators in novel class of systems which can survive up to higher temperatures. Show Chinese abstract

Abstract: 电子关联与自旋轨道耦合的协同作用可以稳定磁性拓扑绝缘体，这类材料表现出诸如量子反常霍尔态（也称为陈绝缘体 CI）等新奇的量子现象。 在这里，我们研究重费米子材料中具有反铁磁（AF）有序的磁性拓扑绝缘体的存在性。 我们的分析基于填充半满的 Kane-Mele-Kondo (KMK) 模型，并考虑了反铁磁 Kondo 相互作用$J_{\rm K}$，该相互作用将局域电子的自旋与每个晶格点上的局域自旋$S=1/2$耦合。 我们考虑了奈尔反铁磁（Néel AF）有序态，其中局域磁化不仅垂直于（$z$-AF 有序），而且平行于（$xy$-AF 有序）蜂窝状平面。 我们表明，在蜂窝结构的两个亚晶格之间没有能量偏移的情况下，系统总是拓扑平凡的。 当增加$J_{\rm K}$时，系统从平凡的$xy$-AF 绝缘体（$xy$-AFI）过渡到平凡的 Kondo 绝缘体（KI）。 我们揭示出一种交替亚晶格势可以导致$z$-AFCI 和$z$-AF量子自旋霍尔绝缘体 ($z$-AFQSHI) 的稳定性。 我们研究了KMK模型中块体以及边缘处的电荷激发。 我们在重费米子材料中的AFCI电荷隙大小与过渡金属化合物中的AFCI电荷隙大小之间进行了系统的比较。 我们的发现能够指导未来寻找能够在更高温度下存在的新型系统中的反铁磁拓扑绝缘体的实验研究。