Elucidating the relationship between spin excitations and fermiology is essential for clarifying the pairing mechanism in iron-based superconductors(FeSCs).Here,we report inelastic neutron scattering results on the ho...Elucidating the relationship between spin excitations and fermiology is essential for clarifying the pairing mechanism in iron-based superconductors(FeSCs).Here,we report inelastic neutron scattering results on the hole overdoped Ba_(0.4)K_(0.6)Fe_(2)As_(2) near a Lifshitz transition,where the electron pocket at M point is nearly replaced by four hole pockets.In the normal state,the spin excitations is observed at incommensurate wave vectors with a chimney-like dispersion.By cooling down to the superconducting state,a neutron spin resonance mode emerges with a peak energy of Er=14-15 meV,weakly modulated along the L-direction.The incommensurability notably increases at low energies,giving rise to downward dispersions of the resonance mode.This behavior contrasts sharply with the upward dispersions of resonance observed in optimally doped Ba_(0.67)K_(0.33)Fe_(2)As_(2) contributed by the hole to electron scattering,but resembles those in KFe_(2)As_(2) and KCa_(2)Fe_(4)As_(4)F_(2) where the fermiology is dominated by hole pockets.These results highlight the critical role of electronic structure modifications near the Fermi level,especially in governing interband scattering under imperfect nesting conditions,which fundamentally shape the spin dynamics of FeSCs.展开更多
We report a reproducible approach in preparing high-quality overdoped Bi2 Sr2 CaCu2 08＋δ （Bi2212） single crystals by annealing Bi2212 crystals in high oxygen pressure followed by a fast quenching. In this way, hig...We report a reproducible approach in preparing high-quality overdoped Bi2 Sr2 CaCu2 08＋δ （Bi2212） single crystals by annealing Bi2212 crystals in high oxygen pressure followed by a fast quenching. In this way, high-quality overdoped and heavily overdoped Bi2212 single crystals are obtained by controlling the annealing oxygen pressure. We find that, beyond a limit of oxygen pressure that can achieve most heavily overdoped Bi2212 with a Tc N63 K, the annealed Bi2212 begins to decompose. This accounts for the existence of the hole-doping limit and thus the Tc limit in the heavily overdoped region of Bi2212 by the oxygen annealing process. These results provide a reliable way in preparing high-quality overdoped and heavily overdoped Bi2212 crystals that are important for studies of the physical properties, electronic structure and superconductivity mechanism of the cuprate superconductors.展开更多
Using band structure parameters extracted from photoemission data by Yoshida et al., Phys. Rev. B., 2006, we have analyzed the temperature dependence of the superfluid density in overdoped La2-xSrxCuO4. We point out t...Using band structure parameters extracted from photoemission data by Yoshida et al., Phys. Rev. B., 2006, we have analyzed the temperature dependence of the superfluid density in overdoped La2-xSrxCuO4. We point out that the temperature behavior 1/λab2 is very sensitive to the ratio 2?0/kBTc and have estimated this quantity, using experimental data obtained previously by Panagopoulos et al., Phys. Rev. B., 1999. We compare the results with those obtained from NMR / NQR (Nuclear Magnetic Resonance / Nuclear Quadrupole Resonance) (Mayer et al., J. Phys, Cond. Mat., 2007) and scanning tunneling spectros-copy (Kato et al., Physica C, 2007) data.展开更多
基金supported by the National Key Research and Development Program of China(Grant Nos.2023YFA1406100,2018YFA0704200,2022YFA1403400 and 2021YFA1400400)the National Natural Science Foundation of China(Grant Nos.11822411 and 12274444)+2 种基金the Strategic Priority Research Program(B)of the CAS(Grant Nos.XDB25000000 and XDB33000000)K.C.Wong Education Foundation(GJTD-2020-01)AP by HBNI-RRCAT and MPCST under the FTYS program。
文摘Elucidating the relationship between spin excitations and fermiology is essential for clarifying the pairing mechanism in iron-based superconductors(FeSCs).Here,we report inelastic neutron scattering results on the hole overdoped Ba_(0.4)K_(0.6)Fe_(2)As_(2) near a Lifshitz transition,where the electron pocket at M point is nearly replaced by four hole pockets.In the normal state,the spin excitations is observed at incommensurate wave vectors with a chimney-like dispersion.By cooling down to the superconducting state,a neutron spin resonance mode emerges with a peak energy of Er=14-15 meV,weakly modulated along the L-direction.The incommensurability notably increases at low energies,giving rise to downward dispersions of the resonance mode.This behavior contrasts sharply with the upward dispersions of resonance observed in optimally doped Ba_(0.67)K_(0.33)Fe_(2)As_(2) contributed by the hole to electron scattering,but resembles those in KFe_(2)As_(2) and KCa_(2)Fe_(4)As_(4)F_(2) where the fermiology is dominated by hole pockets.These results highlight the critical role of electronic structure modifications near the Fermi level,especially in governing interband scattering under imperfect nesting conditions,which fundamentally shape the spin dynamics of FeSCs.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11190022,11334010 and 11534007the National Basic Research Program of China under Grant No 2015CB921000the Strategic Priority Research Program(B)of Chinese Academy of Sciences under Grant No XDB07020300
文摘We report a reproducible approach in preparing high-quality overdoped Bi2 Sr2 CaCu2 08＋δ （Bi2212） single crystals by annealing Bi2212 crystals in high oxygen pressure followed by a fast quenching. In this way, high-quality overdoped and heavily overdoped Bi2212 single crystals are obtained by controlling the annealing oxygen pressure. We find that, beyond a limit of oxygen pressure that can achieve most heavily overdoped Bi2212 with a Tc N63 K, the annealed Bi2212 begins to decompose. This accounts for the existence of the hole-doping limit and thus the Tc limit in the heavily overdoped region of Bi2212 by the oxygen annealing process. These results provide a reliable way in preparing high-quality overdoped and heavily overdoped Bi2212 crystals that are important for studies of the physical properties, electronic structure and superconductivity mechanism of the cuprate superconductors.
文摘Using band structure parameters extracted from photoemission data by Yoshida et al., Phys. Rev. B., 2006, we have analyzed the temperature dependence of the superfluid density in overdoped La2-xSrxCuO4. We point out that the temperature behavior 1/λab2 is very sensitive to the ratio 2?0/kBTc and have estimated this quantity, using experimental data obtained previously by Panagopoulos et al., Phys. Rev. B., 1999. We compare the results with those obtained from NMR / NQR (Nuclear Magnetic Resonance / Nuclear Quadrupole Resonance) (Mayer et al., J. Phys, Cond. Mat., 2007) and scanning tunneling spectros-copy (Kato et al., Physica C, 2007) data.
