Collective density-wave excitations in two-leg Sr14-xCaxCu24O41 ladders.

Microwave and millimeter wave spectroscopy in the slightly hole - doped ladders of Sr 14 Cu 24 O 41

– We have measured the temperatureand frequency dependence of the microwave and millimeter wave conductivity σ1(T, ω) along both the ladder (c-axis) and the leg (a-axis) directions in Sr14Cu24O41. Below a temperature T ∗(∼170 K), we observed a stronger frequency dependence in σc 1(T, ω) than that in σ a 1 (T, ω), forming a small resonance peak developed between 30 GHz and 100 GHz. We also obser...

Commensuration effects on the Wigner crystallization in the ladders and mechanism of charge density wave in the chains of the doped ladder in Sr14-xCaxCu24O41

Quantum Spin Systems: From Spin Gaps to Pseudo Gaps

Many low dimensional spin systems with a dimerized or ladder-like antiferromagnetic exchange coupling have a gapped excitation spectrum with magnetic bound states within the spin gap. For spin ladders with an even number of legs the existence of spin gaps and within the t-J model a tendency toward superconductivity with d-wave symmetry is predicted. In the following we will characterize the spi...

Experiments on Ladders Reveal a Complex Interplay between a Spin-gapped Normal State and Superconductivity

In recent years, the study of ladder materials has developed into a well-established area of research within the general context of Strongly Correlated Electrons. This effort has been triggered by an unusual cross-fertilization between theory and experiments. In this paper, the main experimental results obtained in the context of ladders are reviewed from the perspective of a theorist. Emphasis...

Spin dynamics and sliding density wave in Sr Cu O ladders

Sr Cu O ladder compounds contain linear frag ments of copper oxide planes In contrast to the two dimensional antiferromagnetic cuprates the spin two leg ladders have short range magnetic order and a spin gap Holes doped into these ladders pair and superconduct at high doping concentrations while insulators are known to result from low hole concen trations The competition between insulating stat...