Nuclear β-decay half-lives are predicted based on an empirical formula and the mass predictions from various nuclear models.It is found that the empirical formula can reproduce the nuclearβ-decay half-lives well,esp...Nuclear β-decay half-lives are predicted based on an empirical formula and the mass predictions from various nuclear models.It is found that the empirical formula can reproduce the nuclearβ-decay half-lives well,especially for short-lived nuclei with T_(1/2)<1s.The theoretical half-life uncertainties fromβ-decay energies and the parameters of the empirical formula are further investigated.It is found that the uncertainties of the half-lives are relatively large for heavy nuclei and nuclei near the neutron-drip line.For nuclei on the r-process path,the uncertainties for those with N=126 are about one order of magnitude,which are much larger than the uncertainties for those with N=50 and 82.However,theoretical uncertainties from the parameters of the empirical formula are relatively small for the nuclei on the r-process path,which indicates that the empirical formula is very suitable for predicting theβ-decay half-lives in r-process simulations.展开更多
The band structure in a kagome lattice can naturally exhibit flat band,Dirac cones,and van Hove singularity,enabling rich interplays between correlation and topology.However,the flat band is rarely detected just at th...The band structure in a kagome lattice can naturally exhibit flat band,Dirac cones,and van Hove singularity,enabling rich interplays between correlation and topology.However,the flat band is rarely detected just at the Fermi level in kagome materials,which would be crucial to realize emergent flat band physics.Here,combining angle-resolved photoemission spectroscopy,transport measurements and first-principles calculation,we observe a striking Fermi-level flat band in paramagnetic YCr_(6)Ge_(6)as a typical signature of electronic kagome lattice.We explicitly unveil that orbital character plays an essential role to realize electronic kagome lattice in crystals with transition-metal kagome layers.We further engineer this material with magnetic rare earth elements to break the time-reversal symmetry of the Fermi-level kagome flat band.Our work establishes a Fermi-level flat band in a kagome magnet as an exciting quantum platform.展开更多
基金Partly supported by the National Natural Science Foundation of China under(11805004,11875070)the Key Research Foundation of Education Ministry of Anhui Province(KJ2020A0485)the Open fund for Discipline Construction,Institute of Physical Science and Information Technology,Anhui University.
文摘Nuclear β-decay half-lives are predicted based on an empirical formula and the mass predictions from various nuclear models.It is found that the empirical formula can reproduce the nuclearβ-decay half-lives well,especially for short-lived nuclei with T_(1/2)<1s.The theoretical half-life uncertainties fromβ-decay energies and the parameters of the empirical formula are further investigated.It is found that the uncertainties of the half-lives are relatively large for heavy nuclei and nuclei near the neutron-drip line.For nuclei on the r-process path,the uncertainties for those with N=126 are about one order of magnitude,which are much larger than the uncertainties for those with N=50 and 82.However,theoretical uncertainties from the parameters of the empirical formula are relatively small for the nuclei on the r-process path,which indicates that the empirical formula is very suitable for predicting theβ-decay half-lives in r-process simulations.
基金supported by the Ministry of Science and Technology of China(Grants No.2018YFA0307000,and No.2018FYA0305800)the Innovation Program for Quantum Science and Technology(No.2021ZD0302802)+1 种基金the National Natural Science Foundation of China(Grants No.U2032128,and No.11874047)the Fundamental Research Funds for the Central Universities(Grant No.2042021kf0210).
文摘The band structure in a kagome lattice can naturally exhibit flat band,Dirac cones,and van Hove singularity,enabling rich interplays between correlation and topology.However,the flat band is rarely detected just at the Fermi level in kagome materials,which would be crucial to realize emergent flat band physics.Here,combining angle-resolved photoemission spectroscopy,transport measurements and first-principles calculation,we observe a striking Fermi-level flat band in paramagnetic YCr_(6)Ge_(6)as a typical signature of electronic kagome lattice.We explicitly unveil that orbital character plays an essential role to realize electronic kagome lattice in crystals with transition-metal kagome layers.We further engineer this material with magnetic rare earth elements to break the time-reversal symmetry of the Fermi-level kagome flat band.Our work establishes a Fermi-level flat band in a kagome magnet as an exciting quantum platform.
