Discovering new materials with desirable band gap and gap state is a central task in the semiconductor community,primarily relying on composition modulation.In this work,by employing atomic simulations,using transitio...Discovering new materials with desirable band gap and gap state is a central task in the semiconductor community,primarily relying on composition modulation.In this work,by employing atomic simulations,using transition-metal dichalcogenide Re_(0.5)Nb_(0.5)(S_(0.5)X_(0.5))_(2)(X=Se,Te)monolayer as an example,we present an alternative avenue for gap state engineering via leveraging diverse chemical short-range orders(SROs).It is found the electronic state contributed by the SRO motif tends to be occupied and may merge with the valence band,yielding a clean band gap in these multicomponent systems.On the contrary,the energy unfavorable local configurations,can produce localized states.The chemical environment in the chalcogen sublattice which has negligible influence on the band gap size can further fine-tune the gap states.The strong coupling of multiple short-range orders and gap states revealed in our work unlock the potential application of a vast family of multicomponent semiconductors.展开更多
The vanadium-based kagome superconductor CsV_(3)Sb_(5) has attracted tremendous attention due to its unexcepted anomalous Hall effect(AHE),charge density waves(CDWs),nematicity,and a pseudogap pair density wave(PDW)co...The vanadium-based kagome superconductor CsV_(3)Sb_(5) has attracted tremendous attention due to its unexcepted anomalous Hall effect(AHE),charge density waves(CDWs),nematicity,and a pseudogap pair density wave(PDW)coexisting with unconventional strong-coupling superconductivity.The origins of CDWs,unconventional superconductivity,and their correlation with different electronic states in this kagome system are of great significance,but so far,are still under debate.Chemical doping in the kagome layer provides one of the most direct ways to reveal the intrinsic physics,but remains unexplored.Here,we report,for the first time,the synthesis of Ti-substituted CsV_(3)Sb_(5) single crystals and its rich phase diagram mapping the evolution of intertwining electronic states.The Ti atoms directly substitute for V in the kagome layers.CsV_(3-x)Ti_(x)Sb_(5) shows two distinct superconductivity phases upon substitution.The Ti slightly-substituted phase displays an unconventional V-shaped superconductivity gap,coexisting with weakening CDW,PDW,AHE,and nematicity.The Ti highly-substituted phase has a U-shaped superconductivity gap concomitant with a short-range rotation symmetry breaking CDW,while long-range CDW,twofold symmetry of in-plane resistivity,AHE,and PDW are absent.Furthermore,we also demonstrate the chemical substitution of V atoms with other elements such as Cr and Nb,showing a different modulation on the superconductivity phases and CDWs.These findings open up a way to synthesise a new family of doped CsV_(3)Sb_(5) materials,and further represent a new platform for tuning the different correlated electronic states and superconducting pairing in kagome superconductors.展开更多
基金supported by the National KeyR&D Program of China(2022ZD0117601)Beijing Natural Science Foundation(Z210018)National Natural Science Foundation of China(No.52173216).
文摘Discovering new materials with desirable band gap and gap state is a central task in the semiconductor community,primarily relying on composition modulation.In this work,by employing atomic simulations,using transition-metal dichalcogenide Re_(0.5)Nb_(0.5)(S_(0.5)X_(0.5))_(2)(X=Se,Te)monolayer as an example,we present an alternative avenue for gap state engineering via leveraging diverse chemical short-range orders(SROs).It is found the electronic state contributed by the SRO motif tends to be occupied and may merge with the valence band,yielding a clean band gap in these multicomponent systems.On the contrary,the energy unfavorable local configurations,can produce localized states.The chemical environment in the chalcogen sublattice which has negligible influence on the band gap size can further fine-tune the gap states.The strong coupling of multiple short-range orders and gap states revealed in our work unlock the potential application of a vast family of multicomponent semiconductors.
基金supported by grants from the National Natural Science Foundation of China(61888102,52022105,51771224,11888101,12061131005,and 11834016)the National Key Research and Development Projects of China(2018YFA0305800 and 2019YFA0308500)+6 种基金the Chinese Academy of Sciences(XDB33030100,XDB28010200,and XDB30010000)the Key Research Program of Chinese Academy of Sciences(ZDBS-SSWWHC001)the CAS Project for Young Scientists in Basic Research(YSBR-003)the Beijing Outstanding Young Scientist Program(BJJWZYJH01201914430039)supported by the US DOE,Basic Energy Sciences Grant(DE-FG02-99ER45747)the financial support by the European Research Council(ERC Consolidator Grant,No.815869)the Israel Science Foundation(ISF No.1251/19)。
文摘The vanadium-based kagome superconductor CsV_(3)Sb_(5) has attracted tremendous attention due to its unexcepted anomalous Hall effect(AHE),charge density waves(CDWs),nematicity,and a pseudogap pair density wave(PDW)coexisting with unconventional strong-coupling superconductivity.The origins of CDWs,unconventional superconductivity,and their correlation with different electronic states in this kagome system are of great significance,but so far,are still under debate.Chemical doping in the kagome layer provides one of the most direct ways to reveal the intrinsic physics,but remains unexplored.Here,we report,for the first time,the synthesis of Ti-substituted CsV_(3)Sb_(5) single crystals and its rich phase diagram mapping the evolution of intertwining electronic states.The Ti atoms directly substitute for V in the kagome layers.CsV_(3-x)Ti_(x)Sb_(5) shows two distinct superconductivity phases upon substitution.The Ti slightly-substituted phase displays an unconventional V-shaped superconductivity gap,coexisting with weakening CDW,PDW,AHE,and nematicity.The Ti highly-substituted phase has a U-shaped superconductivity gap concomitant with a short-range rotation symmetry breaking CDW,while long-range CDW,twofold symmetry of in-plane resistivity,AHE,and PDW are absent.Furthermore,we also demonstrate the chemical substitution of V atoms with other elements such as Cr and Nb,showing a different modulation on the superconductivity phases and CDWs.These findings open up a way to synthesise a new family of doped CsV_(3)Sb_(5) materials,and further represent a new platform for tuning the different correlated electronic states and superconducting pairing in kagome superconductors.
