Giant magnetic field from moiré induced Berry phase in homobilayer semiconductors  

作　　者：Hongyi Yu Mingxing Chen Wang Yao 

机构地区：[1]Department of Physics,University of Hong Kong,China [2]School of Physics and Electronics,Hunan Normal University,Changsha 410081,China

出　　处：《National Science Review》2020年第1期12-20,共9页国家科学评论（英文版）

基　　金：supported by the Research Grants Council of Hong Kong(17306819);Croucher Foundation and Seed Funding for Strategic Interdisciplinary Research Scheme of HKU

摘　　要：When quasiparticles move in condensed matters,the texture of their internal quantum structure as a function of position and momentum can give rise to Berry phases that have profound effects on the material’s properties.Seminal examples include the anomalous Hall and spin Hall effects from the momentum-space Berry phases in homogeneous crystals.Here,we explore a conjugate form of the electron Berry phase arising from the moirépattern:the texture of atomic configurations in real space.In homobilayer transition metal dichalcogenides,we show that the real-space Berry phase from moirépatterns manifests as a periodic magnetic field with magnitudes of up to hundreds of Tesla.This quantity distinguishes moirépatterns from different origins,which can have an identical potential landscape,but opposite quantized magnetic flux per supercell.For low-energy carriers,the homobilayer moirés realize topological flux lattices for the quantum-spin Hall effect.An interlayer bias can continuously tune the spatial profile of the moirémagnetic field,whereas the flux per supercell is a topological quantity that can only have a quantized jump observable at a moderate bias.We also reveal the important role of the non-Abelian Berry phase in shaping the energy landscape in small moirépatterns.Our work points to new possibilities to access ultra-high magnetic fields that can be tailored to the nanoscale by electrical and mechanical controls.When quasiparticles move in condensed matters, the texture of their internal quantum structure as a function of position and momentum can give rise to Berry phases that have profound effects on the material’s properties. Seminal examples include the anomalous Hall and spin Hall effects from the momentum-space Berry phases in homogeneous crystals. Here, we explore a conjugate form of the electron Berry phase arising from the moiré pattern: the texture of atomic configurations in real space. In homobilayer transition metal dichalcogenides, we show that the real-space Berry phase from moiré patterns manifests as a periodic magnetic field with magnitudes of up to hundreds of Tesla. This quantity distinguishes moiré patterns from different origins, which can have an identical potential landscape, but opposite quantized magnetic flux per supercell. For low-energy carriers, the homobilayer moirés realize topological flux lattices for the quantum-spin Hall effect. An interlayer bias can continuously tune the spatial profile of the moiré magnetic field, whereas the flux per supercell is a topological quantity that can only have a quantized jump observable at a moderate bias. We also reveal the important role of the non-Abelian Berry phase in shaping the energy landscape in small moiré patterns. Our work points to new possibilities to access ultra-high magnetic fields that can be tailored to the nanoscale by electrical and mechanical controls.

关 键 词：two-dimensional materials transition metal DICHALCOGENIDES moirépattern BERRY phase quantum HALL effect 

分 类 号：O469[理学—凝聚态物理]