Spontaneous isospin polarization and quantum Hall ferromagnetism in a rhombohedral trilayer graphene superlattice
Spontaneous isospin polarization and quantum Hall ferromagnetism in a rhombohedral trilayer graphene superlattice
复制标题
DOI：
10.1088/1674-1056/acddcf
复制
发表时间：
2023-06
影响因子：
1.7
通讯作者：
X. Han 韩;Q. Liu 刘;Ruirui 锐锐 Niu 牛;Zhuangzhuang 壮壮 Qu 曲;Zhiyu 知雨 Wang 王;Z. Li 李;Chunrui 春蕊 Han 韩;Kenji Watanabe;T. Taniguchi;Z. Gan 甘;Jianming 建明 Lu 路
中科院分区：
文献类型：
--
作者：
X. Han 韩;Q. Liu 刘;Ruirui 锐锐 Niu 牛;Zhuangzhuang 壮壮 Qu 曲;Zhiyu 知雨 Wang 王;Z. Li 李;Chunrui 春蕊 Han 韩;Kenji Watanabe;T. Taniguchi;Z. Gan 甘;Jianming 建明 Lu 路
货车德瓦耳斯异质结构中的莫尔超晶格最近引起了人们极大的兴趣，这是由于高度可控的电子关联引起了超导电性、铁磁性和非平凡的拓扑性质。为了深入理解这种奇异的性质，有必要澄清普遍存在于这些基态中的自旋和谷味之间的对称性破缺。在这里，在与六方氮化硼晶体对齐的菱形三层石墨烯中，我们报告了由位移场（D）和磁场调谐的各种类型的破缺跃迁：（i）虽然众所周知，有限的D可以增强相关性，从而在平坦带的分数填充处产生相关绝缘体，但我们发现在正D处，相关间隙在味道被完全填充之前出现，但在负D处顺序颠倒。(ii)在零D附近，窄的朗道能级可以引起电子相关，导致量子霍尔铁磁性，它提升了所有的简并性，不仅包括自旋和谷，还包括轨道自由度。我们的结果揭示了破缺相之间跃迁的复杂性，揭示了强关联系统中各种奇异现象的机制。
Moiré superlattices in van der Waals heterostructures have recently attracted enormous interests, due to the highly controllable electronic correlation that gives rise to superconductivity, ferromagnetism, and nontrivial topological properties. To gain a deep understanding of such exotic properties, it is essential to clarify the broken symmetry between spin and valley flavors which universally exists in these ground states. Here in a rhombohedral trilayer graphene crystallographically aligned with a hexagonal boron nitride, we report various kinds of symmetry-breaking transition tuned by displacement fields (D) and magnetic fields: (i) While it is well known that a finite D can enhance correlation to result in correlated insulators at fractional fillings of a flat band, we find the correlation gap emerges before the flavor is fully filled at a positive D, but the sequence is reversed at a negative D. (ii) Around zero D, electronic correlation can be invoked by narrow Landau levels, leading to quantum Hall ferromagnetism that lifts all the degeneracies including not only spin and valley but also orbital degrees of freedom. Our result unveils the complication of transitions between symmetry-breaking phases, shedding light on the mechanisms of various exotic phenomena in strongly correlated systems.