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封东来, N.
PHYSICAL REVIEW LETTERS VOLUME 87, NUMBER 14, 1 OCTOBER 2001,-0001,():
-1年11月30日
We report a high-resolution angle-resolved photoemission spectroscopic study of the electron-doped (n-type) cuprate superconductor Nd1.85Ce0.15CuO4. We observe regions along the Fermi surface where the near-EF intensity is suppressed and the spectral features are broad in a manner reminiscent of the high-energy “pseudogap” in the underdoped p-type (hole doped) cuprates. However, instead of occurring near the (π,0) region, as in the p-type materials, this pseudogap falls near the intersection of the underlying Fermi surface with the antiferromagnetic Brillouin zone boundary.
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【期刊论文】Bilayer Splitting in the Electronic Structure of Heavily Overdoped Bi2Sr2CaCu2O8+δ
封东来, D.
PHYSICAL REVIEW LETTERS VOLUME 86, NUMBER 24, 11 JUNE 2001,-0001,():
-1年11月30日
The electronic structure of heavily overdoped Bi2Sr2CaCu2O8+δ is investigated by angle-resolved photoemission spectroscopy. The long-sought bilayer band splitting in this two-plane system is observed in both normal and superconducting states, which qualitatively agrees with the bilayer Hubbard model calculations. The maximum bilayer energy splitting is about 88 meV for the normal state feature, while it is only about 20 meV for the superconducting peak.
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封东来, N.
PHYSICAL REVIEW LETTERS VOLUME 88, NUMBER 25, 24 JUNE 2002,-0001,():
-1年11月30日
We present an angle-resolved photoemission doping dependence study of the n-type cuprate superconductor Nd2-xCexCuO4±δ, from the half-filled Mott insulator to the Tc=24 K superconductor. In Nd2CuO4, we reveal the charge-transfer band for the first time. As electrons are doped into the system, this feature's intensity decreases with the concomitant formation of near-EF spectral weight. At low doping, the Fermi surface is an electron-pocket (with volume~x) centered at [π,0]. Further doping leads to the creation of a new holelike Fermi surface (volume~1+x) centered at [π,π]. These findings shed light on the Mott gap, its doping evolution, as well as the anomalous transport properties of the n-type cuprates.
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封东来, J.
PHYSICAL REVIEW B 73, 161104 (R) (2006),-0001,():
-1年11月30日
We report on resonant inelastic x-ray scattering studies of a one-dimensional quantum spin system Sr2CuO3. Data were taken at the Cu 1s→3d edge, which is expected to provide dd excitation spectra. The energy loss spectra show the lowest peak near 2.0 eV, smaller by≈0.6 eV than the lowest energy peak obtained at the 1s→4p edge. The feature has a total dispersion of about 0.2 eV with a periodicity of. While a comparison with optical measurements supports the interpretation of the data as being from dd excitations, the dispersion is apparently incompatible with theoretical results.
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封东来, H.
PHYSICAL REVIEW B 69, 064512 (2004),-0001,():
-1年11月30日
We examine the effect on the superconducting transition temperature (Tc) of chemical inhomogeneities in Bi2Sr2CuO6+δ and Bi2Sr2CaCu2O8+δ single crystals. Cation disorder at the Sr crystallographic site is inherent in these materials and strongly affects the value of Tc. Partial substitution of Sr by Ln(Ln=La, Pr, Nd, Sm, Eu, Gd, and Bi) in Bi2Sr1.6Ln0.4CuO6+δ results in a monotonic decrease of Tc with increasing ionic radius mismatch. By minimizing Sr site disorder at the expense of Ca site disorder, we demonstrate that the Tc of Bi2Sr2CaCu2O8+δ can be increased to 96 K. Based on these results we discuss the effects of chemical inhomogeneity in other bulk high-temperature superconductors.
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