Programming correlated magnetic states with gate-controlled moiré geometry

Understanding quantum many-body systems is at the heart of condensed matter physics. The ability to control the underlying lattice geometry of a system, and thus its many-body interactions, would enable the realization of, and transition between, emergent quantum ground states. Here, we report in-situ gate switching between honeycomb and triangular lattice geometries of an electron many-body Hamiltonian in R-stacked MoTe2 moiré bilayers, resulting in switchable magnetic exchange interactions. At zero electric field, we observe a correlated ferromagnetic insulator near one hole per moiré unit cell (v=-1), i.e., a quarter-filled honeycomb lattice, with a widely tunable Curie temperature up to 14K. A fully polarizing layer pseudospin via electric field switches the system into a half-filled triangular lattice with antiferromagnetic interactions. Further doping this layer-polarized superlattice introduces carriers into the empty layer, tuning the antiferromagnetic exchange interaction back ..., ,

理解量子多体系统是凝聚态物理的核心课题。若能调控系统的底层晶格几何结构，进而调控其多体相互作用，便可实现涌现量子基态并在其间切换。本文报道了在R堆叠MoTe₂莫尔双层中，通过原位栅极切换实现电子多体哈密顿量在蜂窝与三角晶格几何结构间的转换，从而产生可切换的磁交换相互作用。在零电场下，我们观察到当每个莫尔单胞含一个空穴（v=-1）时——即四分之一填充蜂窝晶格——存在关联铁磁绝缘体，其居里温度可广泛调控至14K。进一步掺杂该层极化超晶格会向空层引入载流子，从而将反铁磁交换相互作用调回……