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Spectroscopy of reflection-asymmetric nuclei with relativistic energy density functionals
Quadrupole and octupole deformation energy surfaces, low-energy excitation
spectra and transition rates in fourteen isotopic chains: Xe, Ba, Ce, Nd, Sm,
Gd, Rn, Ra, Th, U, Pu, Cm, Cf, and Fm, are systematically analyzed using a
theoretical framework based on a quadrupole-octupole collective Hamiltonian
(QOCH), with parameters determined by constrained reflection-asymmetric and
axially-symmetric relativistic mean-field calculations. The microscopic QOCH
model based on the PC-PK1 energy density functional and -interaction
pairing is shown to accurately describe the empirical trend of low-energy
quadrupole and octupole collective states, and predicted spectroscopic
properties are consistent with recent microscopic calculations based on both
relativistic and non-relativistic energy density functionals. Low-energy
negative-parity bands, average octupole deformations, and transition rates show
evidence for octupole collectivity in both mass regions, for which a
microscopic mechanism is discussed in terms of evolution of single-nucleon
orbitals with deformation.Comment: 36 pages, 21 figures, Accepted for Publication in Physical Review
Signature of high temperature superconductivity in electron doped Sr2IrO4
Sr2IrO4 was predicted to be a high temperature superconductor upon electron
doping since it highly resembles the cuprates in crystal structure, electronic
structure and magnetic coupling constants. Here we report a scanning tunneling
microscopy/spectroscopy (STM/STS) study of Sr2IrO4 with surface electron doping
by depositing potassium (K) atoms. At the 0.5-0.7 monolayer (ML) K coverage, we
observed a sharp, V-shaped gap with about 95% loss of density of state (DOS) at
EFand visible coherence peaks. The gap magnitude is 25-30 meV for 0.5-0.6 ML K
coverage and it closes around 50 K. These behaviors exhibit clear signature of
superconductivity. Furthermore, we found that with increased electron doping,
the system gradually evolves from an insulating state to a normal metallic
state, via a pseudogap-like state and possible superconducting state. Our data
suggest possible high temperature superconductivity in electron doped Sr2IrO4,
and its remarkable analogy to the cuprates.Comment: 11 pages, 5 figure
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