A tunable bilayer Hubbard model in twisted WSe2
A tunable bilayer Hubbard model in twisted WSe2
复制标题
DOI：
10.1038/s41565-022-01180-7
复制
发表时间：
2022-02
影响因子：
38.3
通讯作者：
Yang Xu;Kaifei Kang;Kenji Watanabe;T. Taniguchi;K. Mak;J. Shan
中科院分区：
文献类型：
--
作者：
Yang Xu;Kaifei Kang;Kenji Watanabe;T. Taniguchi;K. Mak;J. Shan
具有平坦电子能带的莫尔材料为研究强关联物理和拓扑提供了一个高度可控的量子系统。特别是具有较大能带偏移量的半导体过渡金属二卤代化合物角定向异质双分子膜实现了单带Hubbard模型。引入新的层自由度有望促进更丰富的相互作用，使亨德物理学、层间激子凝聚和新的超导配对机制成为可能。在本文中，我们报道了扭曲的AB同质双层WSe2中的竞争电子态，它实现了空穴弱层间跳跃极限下的双层Hubbard模型。通过垂直电场的层极化空穴，我们在空穴密度为ν= 1(以莫尔密度为单位)时观察到从激子绝缘体到电荷转移绝缘体的交叉，在ν= 2处观察到从顺磁到反铁磁电荷转移绝缘体的转变，并在1 <；ν<； 2处观察到了层选择性Mott绝缘体的证据。电荷和自旋与外部电场和磁场的独特耦合也表现出巨大的磁电响应。我们的结果为双层Hubbard模型哈密顿量建立了一个新的固态模拟器。
Moiré materials with flat electronic bands provide a highly controllable quantum system for studies of strong-correlation physics and topology. In particular, angle-aligned heterobilayers of semiconducting transition metal dichalcogenides with large band offset realize the single-band Hubbard model. Introduction of a new layer degree of freedom is expected to foster richer interactions, enabling Hund’s physics, interlayer exciton condensation and new superconducting pairing mechanisms to name a few. Here we report competing electronic states in twisted AB-homobilayer WSe2, which realizes a bilayer Hubbard model in the weak interlayer hopping limit for holes. By layer-polarizing holes via a perpendicular electric field, we observe a crossover from an excitonic insulator to a charge-transfer insulator at a hole density ofν= 1 (in units of moiré density), a transition from a paramagnetic to an antiferromagnetic charge-transfer insulator atν= 2 and evidence for a layer-selective Mott insulator at 1 <ν< 2. The unique coupling of charge and spin to external electric and magnetic fields also manifests a giant magnetoelectric response. Our results establish a new solid-state simulator for the bilayer Hubbard model Hamiltonian.