Density wave ground state and fractional fermions in LaAlO3/SrTiO3 heterostructure

Observation of multi Dirac fermion cloning induced by moiré potential in graphene-SiC heterostructure

We reexamine the electronic structure of graphene on SiC substrate by angle-resolved photoemission spectroscopy. We directly observed multiply cloning of Dirac cone, in addition to ones previously attributed to reconstruction. The locations, relative distances and anisotropy of Dirac cone replicas fully agree with the moiré pattern of graphene-SiC heterostructure. Our results provide a straightforward example of moiré potential modulation in engineering electronic structure with Dirac fermions.

Charge Fractionalization in Oxide Heterostructures: A Field Theoretical Model

LaAlO$_{3}$/SrTiO$_{3}$ heterostructure with polar and non-polar constituents has been shown to exhibit interface metallic conductivity due to fractional charge transfer to the interface. The interface reconstruction by electron redistribution along (001) orientation, in which half of an electron is transferred per two dimensional unit cell to the adjacent planes, resulting in a net transfer of half of the charge, to both the interface and top most atomic planes, has been ascribed to a polar discontinuity at the interface in the Polar Catastrophe model. This avoids the divergence of electrosta…

Kondo晶格超导体异质结构中的自旋分数化

Spin fractionalization in a Kondo-lattice superconductor heterostructure

提出利用异质结构工程调节Kondo晶格激发谱，通过强Kondo耦合展开发现近邻诱导超导配对可促使顺磁子分数化为自旋-1/2激发，为强关联电子系统工程提供新途径。

Topological phase transition in Dirac fermionic heterostructures

Materials with non-trivial topology in their electronic structures enforce the existence of helical Dirac fermionic surface states. We discovered emergent topological phases in the stacked structures of topological insulator and band insulator layers where the surface Dirac fermions interact to each other with particular helicity ordering. Using first-principles calculations and a model Lagrangian, we explicitly demonstrated that such helicity ordering occurs in real materials of ternary chalcogen compounds and determines their topological insulating phase. Our results reveal the rich collecti…

Large gap quantum spin Hall insulator, massless Dirac fermions and bilayer graphene analogue in InAs/Ga(In)Sb heterostructures

The quantum spin Hall insulator (QSHI) state has been demonstrated in two semiconductor systems - HgTe/CdTe quantum wells (QWs) and InAs/GaSb QW bilayers. Unlike the HgTe/CdTe QWs, the inverted band gap in InAs/GaSb QW bilayers does not open at the $Γ$ point of the Brillouin zone, preventing the realization of massless Dirac fermions. Here, we propose a new class of semiconductor systems based on InAs/Ga(In)Sb multilayers, hosting a QSHI state, a graphene-like phase and a bilayer graphene analogue, depending on their layer thicknesses and geometry. The QSHI gap in the novel structures can reac…

基于石墨烯的二维异质结构中的Dirac-Rashba费米子与量子谷霍尔绝缘体

Dirac-Rashba fermions and quantum valley Hall insulators in graphene-based 2D heterostructures

本研究通过第一性原理和有效低能模型，在石墨烯/TMD异质结构中实现Dirac-Rashba费米子与量子谷霍尔效应，为二维异质结构的新奇物性探索提供基础。