We utilize high-resolution resonant angle-resolved photoemission spectroscopy(ARPES)to study the band structure and hybridization effect of the heavy-fermion compound Ce2 IrIn8.We observe a nearly flat band at the bin...We utilize high-resolution resonant angle-resolved photoemission spectroscopy(ARPES)to study the band structure and hybridization effect of the heavy-fermion compound Ce2 IrIn8.We observe a nearly flat band at the binding energy of 7 meV below the coherent temperature Tcoh^40 K,which characterizes the electrical resistance maximum and indicates the onset temperature of hybridization.However,the Fermi vector and the Fermi surface volume have little change around Tcoh,which challenges the widely believed evolution from a hightemperature small Fermi surface to a low-temperature large Fermi surface.Our experimental results of the band structure fit well with the density functional theory plus dynamic mean-field theory calculations.展开更多
Exotic quantum phenomena may appear in material systems with multiple orders or phases,where the mutual interactions can give rise to new physics beyond that of each component.Here,we report spectroscopic evidence for...Exotic quantum phenomena may appear in material systems with multiple orders or phases,where the mutual interactions can give rise to new physics beyond that of each component.Here,we report spectroscopic evidence for a unique combination of topology and correlation effects in the kagome superconductor CsV_(3)Sb_(5).Topologically nontrivial surface states are observed near the Fermi energy(E_(F)),indicating that the topological physics may be active upon entering the superconducting state.Flat bands are observed,suggesting that electron correlation effects are also at play in this system.Our results reveal the peculiar electronic structure of CsV_(3)Sb_(5),which holds the potential for realizing Majorana zero modes and anomalous superconducting states in kagome lattices.They also establish CsV_(3)Sb_(5)as a unique platform for exploring the interactions between the charge order,topology,correlation effects and superconductivity.展开更多
Topological materials and topological phases have recently become a hot topic in condensed matter physics.In this work,we report an In-intercalated transition-metal dichalcogenide In_(x)TaSe_(2)(named 112 system),a to...Topological materials and topological phases have recently become a hot topic in condensed matter physics.In this work,we report an In-intercalated transition-metal dichalcogenide In_(x)TaSe_(2)(named 112 system),a topological nodal-line semimetal in the prep seffiffinffi ce of both charge density wave(CDW)and superconductivity.In the x=0.58 sample,the 2×√3 commensurate CDW(CCDW)and the 2×2 CCDW are observed below 116 and 77 K,respectively.Consistent with theoretical calculations,the spin–orbital coupling gives rise to two twofold-degenerate nodal rings(Weyl rings)connected by drumhead surface states,confirmed by angle-resolved photoemission spectroscopy.Our results suggest that the 2×2 CCDW ordering gaps out one Weyl ring in accordance with the CDW band folding,while the other Weyl ring remains gapless with intact surface states.In addition,superconductivity emerges at 0.91 K,with the upper critical field deviating from the s-wave behavior at low temperature,implying possibly unconventional superconductivity.Therefore,we think this type of the 112 system may possess abundant physical states and offer a platform to investigate the interplay between CDW,nontrivial band topology and superconductivity.展开更多
基金Supported by the National Key Research and Development Program of China under Grant Nos 2016YFA0401000,2015CB921300,2016YFA0300303,2016YFA0401002 and 2017YFA0303103the National Natural Science Foundation of China under Grant Nos 11674371,11774401 and 11874330+4 种基金the Strategic Priority Research Program(B)of the Chinese Academy of Sciences under Grant No XDB07000000the Beijing Municipal Science and Technology Commission under Grant No Z171100002017018the Hundred-Talent Program(type C)of the Chinese Academy of Sciencesthe Sino-Swiss Science and Technology Cooperation under Grant No IZLCZ2-170075the Swiss National Science Foundation under Grant No 200021-159678
文摘We utilize high-resolution resonant angle-resolved photoemission spectroscopy(ARPES)to study the band structure and hybridization effect of the heavy-fermion compound Ce2 IrIn8.We observe a nearly flat band at the binding energy of 7 meV below the coherent temperature Tcoh^40 K,which characterizes the electrical resistance maximum and indicates the onset temperature of hybridization.However,the Fermi vector and the Fermi surface volume have little change around Tcoh,which challenges the widely believed evolution from a hightemperature small Fermi surface to a low-temperature large Fermi surface.Our experimental results of the band structure fit well with the density functional theory plus dynamic mean-field theory calculations.
基金supported by the Fundamental Research Funds for the Central Universities(WK3510000012 and WK3510000008)USTC Start-up Fund and National Natural Science Foundation of China(12004363)+6 种基金supported by the Swiss National Science Foundation(200021-188413)the SinoSwiss Science and Technology Cooperation(IZLCZ2-170075)supported via the UC Santa Barbara NSF Quantum Foundry funded via the Q-AMASE-i Program under award DMR-1906325the shared facilities of the NSF Materials Research Science and Engineering Center at UC Santa Barbara(DMR-1720256)supported by NSF CNS-1725797 and NSF DMR-1720256support from the California NanoSystems Institute through the Elings Fellowship programsupported by the National Science Foundation Graduate Research Fellowship Program(DGE-1650114)。
文摘Exotic quantum phenomena may appear in material systems with multiple orders or phases,where the mutual interactions can give rise to new physics beyond that of each component.Here,we report spectroscopic evidence for a unique combination of topology and correlation effects in the kagome superconductor CsV_(3)Sb_(5).Topologically nontrivial surface states are observed near the Fermi energy(E_(F)),indicating that the topological physics may be active upon entering the superconducting state.Flat bands are observed,suggesting that electron correlation effects are also at play in this system.Our results reveal the peculiar electronic structure of CsV_(3)Sb_(5),which holds the potential for realizing Majorana zero modes and anomalous superconducting states in kagome lattices.They also establish CsV_(3)Sb_(5)as a unique platform for exploring the interactions between the charge order,topology,correlation effects and superconductivity.
基金the National Key R&D Program of the China(2016YFA0300402,2014CB648400,and 2016YFA0300203)the National Natural Science Foundation of China(11774305 and 11274006)the Fundamental Research Funds for the Central Universities of China。
文摘Topological materials and topological phases have recently become a hot topic in condensed matter physics.In this work,we report an In-intercalated transition-metal dichalcogenide In_(x)TaSe_(2)(named 112 system),a topological nodal-line semimetal in the prep seffiffinffi ce of both charge density wave(CDW)and superconductivity.In the x=0.58 sample,the 2×√3 commensurate CDW(CCDW)and the 2×2 CCDW are observed below 116 and 77 K,respectively.Consistent with theoretical calculations,the spin–orbital coupling gives rise to two twofold-degenerate nodal rings(Weyl rings)connected by drumhead surface states,confirmed by angle-resolved photoemission spectroscopy.Our results suggest that the 2×2 CCDW ordering gaps out one Weyl ring in accordance with the CDW band folding,while the other Weyl ring remains gapless with intact surface states.In addition,superconductivity emerges at 0.91 K,with the upper critical field deviating from the s-wave behavior at low temperature,implying possibly unconventional superconductivity.Therefore,we think this type of the 112 system may possess abundant physical states and offer a platform to investigate the interplay between CDW,nontrivial band topology and superconductivity.