The recently discovered titanium-based kagome metal ATi_(3)Bi_(5)(A=Cs,Rb)provides a new platform to explore novel quantum phenomena.In this work,the transport properties of ATi_(3)Bi_(5)(A=Cs,Rb)are systematically in...The recently discovered titanium-based kagome metal ATi_(3)Bi_(5)(A=Cs,Rb)provides a new platform to explore novel quantum phenomena.In this work,the transport properties of ATi_(3)Bi_(5)(A=Cs,Rb)are systematically investigated under high pressure.Although ATi_(3)Bi_(5)(A=Cs,Rb)shows no evidence of superconductivity at ambient pressure,the pressure-induced double-dome superconductivity is observed in both compounds,resembling the superconducting phase diagram of AV_(3)Sb_(5)(A=Cs,Rb,and K)under pressure.High-pressure X-ray difraction measurements exclude the pressure-induced structural phase transition.A slope change in the c/a ratio was found between 12.4 and 14.9 GPa,indicating the occurrence of lattice distortion.The distinct changes in the electronic band structure revealed by frst-principles calculations further explain the emergence of superconductivity in the two domes.These fndings suggest that pressure can efectively tune the electronic properties of ATi_(3)Bi_(5),providing new insights into the rich physics of kagome metals.展开更多
V-based kagome superconductors AV_(3)Sb_(5)(A=K,Rb,and Cs)host a charge density wave(CDW)and a topological nontrivial band structure,thereby providing a great platform to study the interplay of superconductivity(SC),C...V-based kagome superconductors AV_(3)Sb_(5)(A=K,Rb,and Cs)host a charge density wave(CDW)and a topological nontrivial band structure,thereby providing a great platform to study the interplay of superconductivity(SC),CDW,frustration,and topology.Here,we report ultralow-temperature thermal conductivity measurements of CsV_(3)Sb_(5 ) and Ta-doped Cs((V_(0.86)Ta_(0.14)))_(3)Sb_(5) and scanning tunneling microscopy(STM)measurements of CsV_(3)Sb_(5 ).The finite residual linear term of thermal conductivity at zero magnetic field suggests the existence of a residual density of states(DOS)in the superconducting state of CsV_(3)Sb_(5 ).This is supported by the observation of non-zero conductance at zero bias in STM spectrum at an electronic temperature of 90 mK.However,in Cs(V_(0.86)Ta_(0.14))_(3)Sb_(5),which does not have CDW order,there is no evidence for the residual DOS.These results show the importance of CDW order for the residual DOS,and that a nodal s-wave gap or residual Fermi arc may be the origin of the residual DOS in such an unusual multiband kagome superconductor,CsV_(3)Sb_(5 ).展开更多
基金supported by the Natural Science Foundation of China(Grant No.12174064)the Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)+5 种基金the Innovation Program for Quantum Science and Technology(Grant No.2024ZD0300104)the support by the Natural Science Foundation of China(Grant No.12204383)the Young Elite Scientists Sponsorship Program by CAST(Grant No.2023QNRC001)the Young Talent Fund of the Association for Science and Technology in Shaanxi(Grant No.CLGC202201)supported by the open project of Beijing National Laboratory for Condensed Matter Physics(Grant No.ZBJ2106110017)the Double First-Class Initiative Fund of Shanghai Tech University。
文摘The recently discovered titanium-based kagome metal ATi_(3)Bi_(5)(A=Cs,Rb)provides a new platform to explore novel quantum phenomena.In this work,the transport properties of ATi_(3)Bi_(5)(A=Cs,Rb)are systematically investigated under high pressure.Although ATi_(3)Bi_(5)(A=Cs,Rb)shows no evidence of superconductivity at ambient pressure,the pressure-induced double-dome superconductivity is observed in both compounds,resembling the superconducting phase diagram of AV_(3)Sb_(5)(A=Cs,Rb,and K)under pressure.High-pressure X-ray difraction measurements exclude the pressure-induced structural phase transition.A slope change in the c/a ratio was found between 12.4 and 14.9 GPa,indicating the occurrence of lattice distortion.The distinct changes in the electronic band structure revealed by frst-principles calculations further explain the emergence of superconductivity in the two domes.These fndings suggest that pressure can efectively tune the electronic properties of ATi_(3)Bi_(5),providing new insights into the rich physics of kagome metals.
文摘V-based kagome superconductors AV_(3)Sb_(5)(A=K,Rb,and Cs)host a charge density wave(CDW)and a topological nontrivial band structure,thereby providing a great platform to study the interplay of superconductivity(SC),CDW,frustration,and topology.Here,we report ultralow-temperature thermal conductivity measurements of CsV_(3)Sb_(5 ) and Ta-doped Cs((V_(0.86)Ta_(0.14)))_(3)Sb_(5) and scanning tunneling microscopy(STM)measurements of CsV_(3)Sb_(5 ).The finite residual linear term of thermal conductivity at zero magnetic field suggests the existence of a residual density of states(DOS)in the superconducting state of CsV_(3)Sb_(5 ).This is supported by the observation of non-zero conductance at zero bias in STM spectrum at an electronic temperature of 90 mK.However,in Cs(V_(0.86)Ta_(0.14))_(3)Sb_(5),which does not have CDW order,there is no evidence for the residual DOS.These results show the importance of CDW order for the residual DOS,and that a nodal s-wave gap or residual Fermi arc may be the origin of the residual DOS in such an unusual multiband kagome superconductor,CsV_(3)Sb_(5 ).
