Recently,the discovery of a variety of moiré-related properties in the twisted vertical stacking of two different monolayers has attracted considerable attention.The introduction of small twist angles in transiti...Recently,the discovery of a variety of moiré-related properties in the twisted vertical stacking of two different monolayers has attracted considerable attention.The introduction of small twist angles in transition metal dichalcogenide(TMD)heterostructures leads to the emergence of moirépotentials,which provide a fascinating platform for the study of strong interactions of electrons.While there has been extensive research on moiréexcitons in twisted bilayer superlattices,the capture and study of moiréexcitons in homostructure superlattices with layer-coupling effects remain elusive.Here,we present the observation of moiréexcitons in the twisted 1L-WSe_(2)/1L-WSe_(2)and 1L-WSe_(2)/2L-WSe_(2)homostructures with various layer-coupling interactions.The results reveal that the moirépotential increases(~260%)as the number of underlying layers decreases,indicating the effect of layer coupling on the modulation of the moirépotential.The effects of the temperature and laser power dependence as well as valley polarization on moiréexcitons were further demonstrated,and the crucial spectral features observed were explained.Our findings pave the way for exploring quantum phenomena and related applications of quantum information.展开更多
Moirésuperlattices in van der Waals structures have emerged as a powerful platform for studying the novel quantum properties of two-dimensional materials.The periodic moirépatterns generated by these structu...Moirésuperlattices in van der Waals structures have emerged as a powerful platform for studying the novel quantum properties of two-dimensional materials.The periodic moirépatterns generated by these structures lead to the formation of flat mini-bands,which alter the electronic energy bands of the material.The resulting flat electronic bands can greatly enhance strong correlative interactions between electrons,leading to the emergence of exotic quantum phenomena,including moiréphonons and moiréexcitons.While extensive research has been conducted on the exotic quantum phenomena in twisted bilayers of transition metal dichalcogenides(TMDs),and the regulatory effect of stacked layers on moiréexcitons remains unexplored.In this study,we report the fabrication of a twisted WSe_(2)/WSe_(2)/WSe_(2) homotrilayer with two twist angles and investigate the influence of stacked layers on moiréexcitons.Our experiments reveal multiple moiréexciton splitting peaks in the twisted trilayer,with moirépotential depths of 78 and 112 meV in the bilayer and trilayer homostructures,respectively.We also observed the splitting of the moiréexcitons at 90 K,indicating the presence of a deeper moirépotential in the twisted trilayer.Moreover,we demonstrate that stacked layers can tune the moiréexcitons by manipulating temperature,laser power,and magnetic field.Our results provide a new physical model for studying moirésuperlattices and their quantum properties,which could potentially pave the way for the development of quantum optoelectronics.展开更多
The stacking of twisted two-dimensional(2D)layered materials has led to the creation of moirésuperlattices,which have become a new platform for the study of quantum optics.The strong coupling of moirésuperla...The stacking of twisted two-dimensional(2D)layered materials has led to the creation of moirésuperlattices,which have become a new platform for the study of quantum optics.The strong coupling of moirésuperlattices can result in flat minibands that boost electronic interactions and generate interesting strongly correlated states,including unconventional superconductivity,Mott insulating states,and moiréexcitons.However,the impact of adjusting and localizing moiréexcitons in Van der Waals heterostructures has yet to be explored experimentally.Here,we present experimental evidence of the localization-enhanced moiréexcitons in the twisted WSe_(2)/WS_(2)/WSe_(2)heterotrilayer with type-II band alignments.At low temperatures,we observed multiple excitons splitting in the twisted WSe_(2)/WS_(2)/WSe_(2)heterotrilayer,which is manifested as multiple sharp emission lines,in stark contrast to the moiréexcitonic behavior of the twisted WSe_(2)/WS_(2)heterobilayer(which has a linewidth 4 times wider).This is due to the enhancement of the two moirépotentials in the twisted heterotrilayer,enabling highly localized moiréexcitons at the interface.The confinement effect of moirépotential on moiréexcitons is further demonstrated by changes in temperature,laser power,and valley polarization.Our findings offer a new approach for localizing moiréexcitons in twist-angle heterostructures,which has the potential for the development of coherent quantum light emitters.展开更多
Exploiting the valley degrees of freedom as information carriers provides new opportunities for the development of valleytronics.Monolayer transition metal dichalcogenides(TMDs)with broken space-inversion symmetry exh...Exploiting the valley degrees of freedom as information carriers provides new opportunities for the development of valleytronics.Monolayer transition metal dichalcogenides(TMDs)with broken space-inversion symmetry exhibit emerging valley pseudospins,making them ideal platforms for studying valley electronics.However,intervalley scattering of different energy valleys limits the achievable degree of valley polarization.Here,we constructed WSe_(2)/yttrium iron garnet(YIG)heterostructures and demonstrated that the interfacial magnetic exchange effect on the YIG magnetic substrate can enhance valley polarization by up to 63%,significantly higher than that of a monolayer WSe_(2)on SiO_(2)/Si(11%).Additionally,multiple sharp exciton peaks appear in the WSe_(2)/YIG heterostructures due to the strong magnetic proximity effect at the magnetic-substrate interface that enhances exciton emission efficiency.Moreover,under the effect of external magnetic field,the magnetic direction of the magnetic substrate enhances valley polarization,further demonstrating that the magnetic proximity effect regulates valley polarization.Our results provide a new way to regulate valley polarization and demonstrate the promising application of magnetic heterojunctions in magneto-optoelectronics.展开更多
基金the National Natural Science Foundation of China(No.61775241)Hunan province key research and development project(No.2019GK2233)+9 种基金Hunan Provincial Science Fund for Distinguished Young Scholars(No.2020JJ2059)the Youth Innovation Team(No.2019012)of CSUthe Science and Technology Innovation Basic Research Project of Shenzhen(No.JCYJ20190806144418859)the National Natural Science Foundation of China(Nos.62090035 and U19A2090)the Key Program of Science and Technology Department of Hunan Province(Nos.2019XK2001 and 2020XK2001)support of the High-Performance Complex Manufacturing Key State Lab Project,Central South University(No.ZZYJKT2020-12)the Australian Research Council(ARC Discovery Project,No.DP180102976)the National Natural Science Foundation of China(No.11974387)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB33000000)the National Key Research and Development Program of China(No.2020YFA0711502).
文摘Recently,the discovery of a variety of moiré-related properties in the twisted vertical stacking of two different monolayers has attracted considerable attention.The introduction of small twist angles in transition metal dichalcogenide(TMD)heterostructures leads to the emergence of moirépotentials,which provide a fascinating platform for the study of strong interactions of electrons.While there has been extensive research on moiréexcitons in twisted bilayer superlattices,the capture and study of moiréexcitons in homostructure superlattices with layer-coupling effects remain elusive.Here,we present the observation of moiréexcitons in the twisted 1L-WSe_(2)/1L-WSe_(2)and 1L-WSe_(2)/2L-WSe_(2)homostructures with various layer-coupling interactions.The results reveal that the moirépotential increases(~260%)as the number of underlying layers decreases,indicating the effect of layer coupling on the modulation of the moirépotential.The effects of the temperature and laser power dependence as well as valley polarization on moiréexcitons were further demonstrated,and the crucial spectral features observed were explained.Our findings pave the way for exploring quantum phenomena and related applications of quantum information.
基金The study presented herein was generously supported by multiple funding agencies,including the National Natural Science Foundation of China(No.61775241)the Hunan Province Key Research and Development Project(No.2019GK2233)+9 种基金the Hunan Provincial Science Fund for Distinguished Young Scholars(No.2020JJ2059)the National Natural Science Foundation of China(Nos.62090035 and U19A2090)the Youth Innovation Team(No.2019012)of CSU,the Key Program of Science and Technology Department of Hunan Province(Nos.2019XK2001 and 2020XK2001)the Science and Technology Innovation Basic Research Project of Shenzhen(No.JCYJ20190806144418859)the Postdoctoral Science Foundation of China(No.2022M713546)The authors also express their gratitude to the High-Performance Complex Manufacturing Key State Lab Project,Central South University(No.ZZYJKT2020-12)the Australian Research Council(ARC Discovery Project,DP180102976)for their support of ZWLCTW is grateful for support from the National Natural Science Foundation of China(No.11974387)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB33000000)H.H.Z.acknowledges support from the Postdoctoral Science Foundation of China(No.2022M713546).
文摘Moirésuperlattices in van der Waals structures have emerged as a powerful platform for studying the novel quantum properties of two-dimensional materials.The periodic moirépatterns generated by these structures lead to the formation of flat mini-bands,which alter the electronic energy bands of the material.The resulting flat electronic bands can greatly enhance strong correlative interactions between electrons,leading to the emergence of exotic quantum phenomena,including moiréphonons and moiréexcitons.While extensive research has been conducted on the exotic quantum phenomena in twisted bilayers of transition metal dichalcogenides(TMDs),and the regulatory effect of stacked layers on moiréexcitons remains unexplored.In this study,we report the fabrication of a twisted WSe_(2)/WSe_(2)/WSe_(2) homotrilayer with two twist angles and investigate the influence of stacked layers on moiréexcitons.Our experiments reveal multiple moiréexciton splitting peaks in the twisted trilayer,with moirépotential depths of 78 and 112 meV in the bilayer and trilayer homostructures,respectively.We also observed the splitting of the moiréexcitons at 90 K,indicating the presence of a deeper moirépotential in the twisted trilayer.Moreover,we demonstrate that stacked layers can tune the moiréexcitons by manipulating temperature,laser power,and magnetic field.Our results provide a new physical model for studying moirésuperlattices and their quantum properties,which could potentially pave the way for the development of quantum optoelectronics.
基金The authors express their gratitude to various organizations for their support in this research,including the National Natural Science Foundation of China(Grant No.61775241)the Hunan province key research and development project(Grant No.2019GK2233)+8 种基金the Hunan Provincial Science Fund for Distinguished Young Scholars(Grant No.2020JJ2059)the Youth Innovation Team(Grant No.2019012)of CSU.Additionally,they acknowledge the Science and Technology Innovation Basic Research Project of Shenzhen(Grant No.JCYJ20190806144418859)the National Natural Science Foundation of China(Nos.62090035 and U19A2090)the Key Program of Science and Technology Department of Hunan Province(2019XK2001,2020XK2001)The authors also thank the High-Performance Complex Manufacturing Key State Lab Project of Central South University(Grant No.ZZYJKT2020-12)for their support.Z.W.Lacknowledges the support from the Australian Research Council(ARC Discovery Project,DP180102976)C.T.W.is grateful for the support from the National Natural Science Foundation of China(Grant No.11974387)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB33000000)H.H.Z.acknowledges the support from the Postdoctoral Science Foundation of China(2022M713546).Finally,the authors recognize the Beijing Super Cloud Computing Center(BSCC)for providing HPC resources,which have greatly contributed to the results reported in this paper.
文摘The stacking of twisted two-dimensional(2D)layered materials has led to the creation of moirésuperlattices,which have become a new platform for the study of quantum optics.The strong coupling of moirésuperlattices can result in flat minibands that boost electronic interactions and generate interesting strongly correlated states,including unconventional superconductivity,Mott insulating states,and moiréexcitons.However,the impact of adjusting and localizing moiréexcitons in Van der Waals heterostructures has yet to be explored experimentally.Here,we present experimental evidence of the localization-enhanced moiréexcitons in the twisted WSe_(2)/WS_(2)/WSe_(2)heterotrilayer with type-II band alignments.At low temperatures,we observed multiple excitons splitting in the twisted WSe_(2)/WS_(2)/WSe_(2)heterotrilayer,which is manifested as multiple sharp emission lines,in stark contrast to the moiréexcitonic behavior of the twisted WSe_(2)/WS_(2)heterobilayer(which has a linewidth 4 times wider).This is due to the enhancement of the two moirépotentials in the twisted heterotrilayer,enabling highly localized moiréexcitons at the interface.The confinement effect of moirépotential on moiréexcitons is further demonstrated by changes in temperature,laser power,and valley polarization.Our findings offer a new approach for localizing moiréexcitons in twist-angle heterostructures,which has the potential for the development of coherent quantum light emitters.
基金The authors would like to acknowledge the National Natural Science Foundation of China(Nos.61775241,62090035,and U19A2090)the Hunan Province Key Research and Development Project(No.2019GK2233)+8 种基金the Hunan Provincial Science Fund for Distinguished Young Scholars(No.2020JJ2059)the Youth Innovation Team of CSU(No.2019012)the Key Program of Science and Technology Department of Hunan Province(Nos.2019XK2001 and 2020XK2001)the Science and Technology Innovation Basic Research Project of Shenzhen(No.JCYJ20190806144418859)the Postdoctoral Science Foundation of China(No.2022M713546)The authors would also like to express their gratitude to the High-Performance Complex Manufacturing Key State Lab Project,Central South University(No.ZZYJKT2020-12)the Australian Research Council(ARC)Discovery Project(No.DP180102976)for their support of Z.W.L.C.T.W.acknowledges support from the National Natural Science Foundation of China(No.11974387)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB33000000)H.H.Z.is grateful for the support from the Postdoctoral Science Foundation of China(No.2022M713546).
文摘Exploiting the valley degrees of freedom as information carriers provides new opportunities for the development of valleytronics.Monolayer transition metal dichalcogenides(TMDs)with broken space-inversion symmetry exhibit emerging valley pseudospins,making them ideal platforms for studying valley electronics.However,intervalley scattering of different energy valleys limits the achievable degree of valley polarization.Here,we constructed WSe_(2)/yttrium iron garnet(YIG)heterostructures and demonstrated that the interfacial magnetic exchange effect on the YIG magnetic substrate can enhance valley polarization by up to 63%,significantly higher than that of a monolayer WSe_(2)on SiO_(2)/Si(11%).Additionally,multiple sharp exciton peaks appear in the WSe_(2)/YIG heterostructures due to the strong magnetic proximity effect at the magnetic-substrate interface that enhances exciton emission efficiency.Moreover,under the effect of external magnetic field,the magnetic direction of the magnetic substrate enhances valley polarization,further demonstrating that the magnetic proximity effect regulates valley polarization.Our results provide a new way to regulate valley polarization and demonstrate the promising application of magnetic heterojunctions in magneto-optoelectronics.