O NMR study of the local charge state in the hole - doped Cu 2 O 3 two - leg spin - ladder A 14 Cu 24 O 41
نویسندگان
چکیده
NMR measurements of the O nuclear quadrupole interactions nQ show that the charge environment of the S51/2 Cu2O3 two-leg spin-ladder layer of hole-doped A14Cu24O41 changes dramatically above a certain temperature T*. This temperature T* decreases with additional doping and is correlated with the magnetic crossover from the spin gap regime to the paramagnetic regime. We demonstrate that these changes in nQ are consistent with an increase in the effective hole concentration in the Cu2O3 two-leg ladder above T*. The effective hole concentration increases primarily in the oxygen 2ps orbitals.
منابع مشابه
A ug 2 00 1 ESR study of ( Sr , La , Ca ) 14 Cu 24 O 41
We report an electron spin resonance (ESR) study of single crystals of the spin-chain spin-ladder compound (Sr, La, Ca) 14 Cu 24 O 41. The data suggest that in intrin-sically hole doped Sr 14−x Ca x Cu 24 O 41 only a small amount of holes is transferred from the chains to the ladders with increasing x, resulting in a crossover from spin dimerized to uniform spin chains. In the samples of La 14−...
متن کاملCollective Spin and Charge Excitations in (Sr,La)14−xCaxCu24O41 Quantum Spin Ladders
In 1988, material research focussed around the study of high temperature superconducting copper-oxides brought about new phases of Cu-O based systems, the two-leg spin-ladders (2LL's), that have the general formula (A 1−x A' x) 14 Cu 24 O 41 , with A an alkaline earth metal and A' a trivalent (transition or lanthanoid) metal [1, 2]. There were well-founded hopes that these materials could provi...
متن کاملMicrowave 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...
متن کاملSpin 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...
متن کاملOptical spectroscopy of ( La , Ca ) 14 Cu 24 O 41 spin ladders : comparison of experiment and theory
Transmission and reflectivity of La x Ca 14−x Cu 24 O 41 two-leg spin-1/2 ladders were measured in the mid-infrared regime between 500 and 12 000 cm −1. This allows us to determine the optical conductivity σ 1 directly and with high sensitivity. Here we show data for x=4 and 5 with the electrical field polarized parallel to the rungs (E || a) and to the legs (E || c). Three characteristic peaks...
متن کامل