Spin excitations in the(Sr,Ca)14Cu24

Phase diagrams of (La,Y,Sr,Ca)14Cu24O41: Switching between the ladders and the chains

“…Holes in the ladders appear as being mobile when compared with the holes in the chains. Gapped spin-liquid (which is a ground state of the undoped ladders) and two-dimensional (2D) charge-density wave (CDW) order set in concomitantly, at least for x ≤ 4, as shown by NMR, and by our charge response studies [28][29][30][31][32][33][34]. This CDW, with periodicity of five ladder unit-cell parameters [35], develops in 2D in the ac ladder planes.…”

“…Both dc resistivity and low frequency dielectric spectroscopy show that increasing the Ca content destroys the long-range order rapidly (for 6 < x ≤ 9) so that only CDW short-range order survives, before it vanishes completely for x > 9 [33,34]. For x > 4 the crossover from gapped spin-liquid to paramagnetic regime remains independent of Ca content and corresponding hole transfer into the ladders [31,32]. Sketched are also metallic and antiferromagnetic phases [17,25] observed for large Ca substitution.…”

Spin rotational symmetry breaking by orbital current patterns in two-leg ladders

“…16,17 On the theoretical side significant efforts were made to probe the possible existence of such a phase, either using numerical approaches [18][19][20] or starting from Mott insulating side. 21 As a way of investigating the physics of these states in a more controlled way and also in view of possible connections with experimental systems, [22][23][24][25][26] phases exhibiting orbital current patterns ͑OCP͒ were also considered in the context of two-leg ladders. 27,28 Indeed for this essentially onedimensional ͑1D͒ case, various analytical tools allow one to explore the consequences of such an unusual phase.…”

Crossover in charge transport from one-dimensional copper-oxygen chains to two-dimensional ladders in(La,Y)y(Sr,CaIvek1, Vuletić2, Korin-Hamzić3 et al. 2008Phys. Rev. B5030View full textAdd to dashboardCite

“…10 Applying pressure also increases interladder coupling leading to metallic transport along both the legs and rungs of the ladders, 11 as well as raises the number of mobile quasiparticles at low temperature. 12,13 These particles have a finite density of states at the Fermi level and might contribute to the superconducting instability. All these results together with an indication for the existence of a Hebel-Slichter coherence peak in the SC state as well as the significant level of disorder in the doped ladders of Sr 14−x Ca x Cu 24 O 41 indicate that the su-perconducting pairing mechanism and symmetry are probably different compared to theoretical predictions for pure single ladders.…”