Related papers: Hole-depletion of ladders in Sr$_{14}$Cu$_{24}$O$_…
The unoccupied electronic structure for the Sr_14Cu_24O_41 family of two-leg ladder compounds was investigated for different partial substitutions of Sr^2+ by Ca^2+, leaving the nominal hole count constant, and by Y^3+ or La^3+, reducing…
The distribution of holes in Sr$_{14-x}$Ca$_x$Cu$_{24}$O$_{41}$ (SCCO) is revisited with semi-emperical reanalysis of the x-ray absorption (XAS) data and exact-diagonalized cluster calculations. A new interpretation of the XAS data leads to…
We report the results of a ^63Cu and ^17O NMR study of the nuclear quadrupole interaction tensor, ^(17,63)nu\_{Q,alpha}, in the hole doped spin ladder system Sr\_(14-x)Ca\_xCu\_24O\_41 (x = 0 and 12) performed under ambient and high…
Structural properties of the spin chain and ladder compound Sr$_{14}$Cu$_{24}$O$_{41}$ have been studied using diffraction with hard x-rays. Strong incommensurate modulation reflections are observed due to the lattice mismatch of the chain…
One of the deepest questions in condensed matter physics concerns what other phases compete with superconductivity in high-transition-temperature (high-Tc) superconductors. One candidate is the "stripe" phase, in which the carriers (holes)…
We examine the electronic states of Sr$_{14-x}$Ca$_x$Cu$_{24}$O$_{41}$ by the ionic and cluster model approach. It is found that self-doped holes are likely to stay on the chain at $x=0$ and the Ca substitution drives the holes to move to…
Recently the superconductivity has been reported in the copper oxides (Sr,Ca)$_{14}$Cu$_{24}$O$_{41}$ with ladders and edge-sharing chains under pressure. In order to understand the mechanism of the superconductivity, it is crucial to…
Neutron scattering experiments have been performed on Sr$_{14}$Cu$_{24}$O$_{41}$ which consists of both chains and ladders of copper ions. We observed that the magnetic excitations from the CuO$_2$ chain have two branches and that both…
The formation of domains comprising alternating 'hole rich' and 'hole poor' ladders recently observed by Scanning Tunneling Microscopy by Kohsaka et al., on lightly hole doped cuprates, is interpreted in terms of an attractive mechanism…
We present Hall-effect measurements of two-leg ladder compounds Sr_{14-x}Ca_xCu_24O_41 (0 <= x <= 11.5) with the aim to determine the number of carriers participating in dc transport. Distribution of holes between the ladder and chain…
We report inelastic light scattering experiments in the spin-chain and ladder system Sr_14-xCa_xCu_24O_41. A depletion of an electronic background is observed for 0 < x < 5 at low temperatures and with light polarization both parallel to…
Starting from the proper charge transfer model for Cu$_2$O$_5$ coupled ladders in Sr$_{14-x}$Ca$_x$Cu$_{24}$O$_{41}$ we derive the low energy Hamiltonian for this system. It occurs that the widely used ladder t-J model is not sufficient and…
We present a polarization-dependent infrared reflectivity study of the spin-ladder compound Sr$_{2.5}$Ca$_{11.5}$Cu$_{24}$O$_{41}$ under pressure. The optical response is strongly anisotropic, with the highest reflectivity along the…
We present a self-consistent treatment of the electron-hole correlations in optically excited quantum wires within the ladder approximation, and using a contact potential interaction. The limitations of the ladder approximation to the…
We have measured the temperature- and frequency dependence of the microwave and millimeter wave conductivity $\sigma_1(T,\omega)$ along both the ladder (c-axis) and the leg (a-axis) directions in Sr$_{14}$Cu$_{24}$O$_{41}$. Below a…
We consider a multiband charge transfer model for a single spin ladder describing the holes in Sr$_{14-x}$Ca$_x$Cu$_{24}$O$_{41}$. Using Hartree-Fock approximation we show how the charge density wave, with its periodicity dependent on…
We present a Monte Carlo study of the correlation length $\xi$ of randomly diluted antiferromagnetic Heisenberg ladders, composed of two spin--1/2 chains. For weak and intermediate inter--chain couplings, $J_{\bot}/J \leq 1$, we find an…
We investigate the binding of holes and the emergence of competing spin-charge order in the simple and extended Hubbard model using exact diagonalization on the 3x4 cylindrical lattice. For the simple Hubbard model (V=0), we find weakly…
The charge transport in the copper-oxygen chain/ladder layers of (La,Y)y(Sr,Ca)14-yCu24O41 is investigated along two crystallographic directions in the temperature range from 50 K to 700 K and for doping levels from y ~= 6 (number of holes…
The "spin ladder" is a reduced-dimensional analogue of the high temperature superconductors that was predicted to exhibit both superconductivity and an electronic charge density wave or "hole crystal" (HC). Both phenomena have been observed…