Mott Gap Excitations and Resonant Inelastic X-Ray Scattering in Doped Cuprates

Predictions are made for the momentum- and carrier-dependent degradation of the Mott gap upon doping in high-Tc cuprates as would be observed in Cu K-edge resonant inelastic x-ray scattering (RIXS). The two-dimensional Hubbard model with second- and third-nearest-neighbor hopping terms has been studied by numerical exact diagonalization. Special emphasis is placed on the particle-hole asymmetry of the Mott gap excitations. We argue that the Mott gap excitations observed by RIXS are significantly influenced by the interaction between charge carriers and antiferromagnetic correlations.Comment: 4 pages, 4 figures, revised version; to be published in Phys. Rev. Let

Computer Calculation of the Transverse Coupling Impedance of Cylindrically Symmetric Structures

A new program called "SUMIRE" which calculates the transverse coupling impedance of cylindrically symmetric structures is presented.The method given here is a simple extention of L.Vos'longitudinal calculation

Longitudinal impedances of some simplified ferrite kicker magnet models

Two simplified models are presented in this paper in order to estimate the contribution of fast kicker magnets to the longitudinal impedance of synchrotrons. The first model is cylindrically symmetric with ferrite surrounding the beam aperture. The beam aperture is rectangular in the second model. Two opposing sides consist of ferrite and the others consist of perfect conductors. The analytical expressions of the longitudinal impedance for the two models are first derived. Subsequently a numerical comparison between these expressions and simulation results obtained with the code HFSS are presented

Some Simplified Models of Ferrite Kicker Magnet for Calculation of Longitudinal Coupling Impedance

Four simplified models of a ferrite kicker magnet are presented to calculate its longitudinal coupling impedance. Also, the impedance measured by coaxial wire methods is estimated and compared with the analytical calculation. The model is evaluated with HFSS simulation

Spin-current absorption by inhomogeneous spin-orbit coupling

We investigate the spin-current absorption induced by an inhomogeneous spin-orbit coupling due to impurities in metals. We consider the system with spin currents driven by the electric field or the spin accumulation. The resulting diffusive spin currents, including the gradient of the spin-orbit coupling strength, indicate the spin-current absorption at the interface, which is exemplified with experimentally relevant setups.Comment: 13 pages, 5 figure

Temperature dependence of spinon and holon excitations in one-dimensional Mott insulators

Motivated by the recent angle-resolved photoemission spectroscopy (ARPES) measurements on one-dimensional Mott insulators, SrCuO${}_{2}$ and Na${}_{0.96}$V${}_{2}$O${}_{5}$, we examine the single-particle spectral weight of the one-dimensional (1D) Hubbard model at half-filling. We are particularly interested in the temperature dependence of the spinon and holon excitations. For this reason, we have performed the dynamical density matrix renormalization group and determinantal quantum Monte Carlo (QMC) calculations for the single-particle spectral weight of the 1D Hubbard model. In the QMC data, the spinon and holon branches become observable at temperatures where the short-range antiferromagnetic correlations develop. At these temperatures, the spinon branch grows rapidly. In the light of the numerical results, we discuss the spinon and holon branches observed by the ARPES experiments on SrCuO${}_{2}$. These numerical results are also in agreement with the temperature dependence of the ARPES results on Na${}_{0.96}$V${}_{2}$O${}_{5}$.Comment: 8 pages, 8 figure

Resonant Two-Magnon Raman Scattering and Photoexcited States in Two-Dimensional Mott Insulators

We investigate the resonant two-magnon Raman scattering in two-dimensional (2D) Mott insulators by using a half-filled 2D Hubbard model in the strong coupling limit. By performing numerical diagonalization calculations for small clusters, we find that the Raman intensity is enhanced when the incoming photon energy is not near the optical absorption edge but well above it, being consistent with experimental data. The absence of resonance near the gap edge is associated with the presence of background spins, while photoexcited states for resonance are found to be characterized by the charge degree of freedom. The resonance mechanism is different from those proposed previously.Comment: REVTeX4, 4 pages, 3 figures, to be published in Phys. Rev. Let

Theoretical study of angle-resolved two-photon photoemission in two-dimensional insulating cuprates

We propose angle-resolved two-photon photoemission spectroscopy (AR-2PPES) as a technique to detect the location of the bottom of the upper Hubbard band (UHB) in two-dimensional insulating cuprates. The AR-2PPES spectra are numerically calculated for small Hubbard clusters. When the pump photon excites an electron from the lower Hubbard band, the bottom of the UHB is less clear, but when an electron in the nonbonding oxygen band is excited, the bottom of the UHB can be identified clearly, accompanied with additional spectra originated from the spin-wave excitation at half filling.Comment: 5 pages, 4 figure

Impedance Evaluation of the SPS MKE Kicker with Transition Pieces between Tank and Kicker Module

In this paper we discuss longitudinal beam coupling impedance measurements performed with the coaxial wire method on a modified prototype of the SPS MKE kicker. The frequency dependent real and imaginary part of the distributed coupling impedance are obtained from the measured S-parameters by standard and improved log-formulae. A comparison with theoretical models and previous measurements is discussed as well