Monolayer group-VIB transition metal dichalcogenides(TMDs)feature low-energy massive Dirac fermions,which have valley contrasting Berry curvature.This nontrivial local band topology gives rise to valley Hall transport...Monolayer group-VIB transition metal dichalcogenides(TMDs)feature low-energy massive Dirac fermions,which have valley contrasting Berry curvature.This nontrivial local band topology gives rise to valley Hall transport and optical selection rules for interband transitions that open up new possibilities for valleytronics.However,the large bandgap in TMDs results in relatively small Berry curvature,leading to weak valley contrasting physics in practical experiments.Here,we show that Dirac fermions with tunable large Berry curvature can be engineered in moirésuperlattice of TMD heterobilayers.These moiréDirac fermions are created in a magnified honeycomb lattice with its sublattice degree of freedom formed by two local moirépotential minima.We show that applying an on-site potential can tune the moiréflat bands into helical ones.In short-period moirésuperlattice,we find that the two moirévalleys become asymmetric,which results in a net spin Hall current.More interestingly,a circularly polarized light drives these moiréDirac fermions into quantum anomalous Hall phase with chiral edge states.Our results open a new possibility to design the moiré-scale spin and valley physics using TMD moiréstructures.展开更多
Determining the number of photons in an incident light pulse at room temperature is the ultimate goal of photodetection.Herein,we report a plasmon-strain-coupled tens of photon level phototransistor by integrating mon...Determining the number of photons in an incident light pulse at room temperature is the ultimate goal of photodetection.Herein,we report a plasmon-strain-coupled tens of photon level phototransistor by integrating monolayer MoS_(2)on top of Au nanowire(NW).Within this structure,Au NW can greatly enhance incident light intensity around MoS_(2),and the large tensile strain can reduce the contact energy barrier between MoS_(2)and Au NW,so as to achieve efficient injection of plasmonic hot electrons into MoS_(2).Furthermore,ultrashort MoS_(2)channel significantly shortens the carrier transit time.As a result,the phototransistor with record optical gain(3.1×10^(11))can accurately determine Poissonian emission statistics of light source with tens of photon level resolution at room temperature.In addition,the phototransistor also demonstrates a broadband spectral sensitivity(0.37–1.55μm),as well as intrinsic photon-polarization selection.Furthermore,an ultra-sensitive optical immunoassay(USOIA)platform is proposed using the phototransistor as photodetector.Coupled with specific antibody-conjugated quantum dot nanospheres and magnetic beads,the platform is able to detect the model biomarker,C-reactive protein,as low as 1.684 amol/L in serum samples with a dynamic range spanning 12 orders of magnitude.With its significantly enhanced sensitivity and simplicity,ultra-high-gain MoS_(2)phototransistor can pave the way toward optically ultra-sensitive determination of various biomarkers for early disease diagnosis.展开更多
基金Project supported by the Science Fund for Distinguished Young Scholars of Hunan Province(Grant No.2022J10002)the National Key Research and Development Program of China(Grant No.2021YFA1200503)the Fundamental Research Funds for the Central Universities from China。
文摘Monolayer group-VIB transition metal dichalcogenides(TMDs)feature low-energy massive Dirac fermions,which have valley contrasting Berry curvature.This nontrivial local band topology gives rise to valley Hall transport and optical selection rules for interband transitions that open up new possibilities for valleytronics.However,the large bandgap in TMDs results in relatively small Berry curvature,leading to weak valley contrasting physics in practical experiments.Here,we show that Dirac fermions with tunable large Berry curvature can be engineered in moirésuperlattice of TMD heterobilayers.These moiréDirac fermions are created in a magnified honeycomb lattice with its sublattice degree of freedom formed by two local moirépotential minima.We show that applying an on-site potential can tune the moiréflat bands into helical ones.In short-period moirésuperlattice,we find that the two moirévalleys become asymmetric,which results in a net spin Hall current.More interestingly,a circularly polarized light drives these moiréDirac fermions into quantum anomalous Hall phase with chiral edge states.Our results open a new possibility to design the moiré-scale spin and valley physics using TMD moiréstructures.
基金supported by the National Key Research and Development Program of the Ministry of Science and Technology(2023YFA0915602)the Creative Research Groups Program of the National Natural Science Foundation of China(62321003)+8 种基金the National Natural Science Foundation of China(62134001,U24A20302,62134001,12174094,62274060,62311540157,32271519,and 62274059)the Natural Science Foundation of Hunan Province(2021RC5004)the Science and Technology Innovation Program of Hunan Province(2023RC3112)the Key Research and Development Plan of Hunan Province(2025WK2013)the Guangdong Basic and Applied Basic Research Foundation(2022B1515020029,2022ZDZX2074,and 2024A1515012157)the Shenzhen Science andTechnology Research Funding(JSGG20201103153801005,JCYJ20220818101413029,and ZDSYS20220527171406014)the Shenzhen Medical Research Fund(B2302028)the Key Laboratory of Biomedical Imaging Science and System,Chinese Academy of Sciences,the Key Laboratory of Nanodevices of Jiangsu Province(ZF2302)the Changsha Municipal Natural Science Foundation(kq2402050).
文摘Determining the number of photons in an incident light pulse at room temperature is the ultimate goal of photodetection.Herein,we report a plasmon-strain-coupled tens of photon level phototransistor by integrating monolayer MoS_(2)on top of Au nanowire(NW).Within this structure,Au NW can greatly enhance incident light intensity around MoS_(2),and the large tensile strain can reduce the contact energy barrier between MoS_(2)and Au NW,so as to achieve efficient injection of plasmonic hot electrons into MoS_(2).Furthermore,ultrashort MoS_(2)channel significantly shortens the carrier transit time.As a result,the phototransistor with record optical gain(3.1×10^(11))can accurately determine Poissonian emission statistics of light source with tens of photon level resolution at room temperature.In addition,the phototransistor also demonstrates a broadband spectral sensitivity(0.37–1.55μm),as well as intrinsic photon-polarization selection.Furthermore,an ultra-sensitive optical immunoassay(USOIA)platform is proposed using the phototransistor as photodetector.Coupled with specific antibody-conjugated quantum dot nanospheres and magnetic beads,the platform is able to detect the model biomarker,C-reactive protein,as low as 1.684 amol/L in serum samples with a dynamic range spanning 12 orders of magnitude.With its significantly enhanced sensitivity and simplicity,ultra-high-gain MoS_(2)phototransistor can pave the way toward optically ultra-sensitive determination of various biomarkers for early disease diagnosis.
