Study on the magnetic susceptibility of quasi-one-dimensional spin ladder compounds (Sr1-xCax)14Cu24O41-δ with oxygen deficiency

Abstract

Three samples of spin ladder compounds (Sr1-xCax)14Cu24O41-δ (x=0, 0.25, 0.43) were prepared by conventional solid-state reaction in air. The EDS results revealed that all three samples are in the state of oxygen deficiency (δ＝7.64，6.99　and 6.67, respectively). X-ray diffraction showed that the samples have single phase, and the lattice parameters a, b, c decrease continuously with the increase of oxygen content. For the sample withoutca Ca doping, the measurement of magnetic susceptibility showed that oxygen deficiency reduces the number of holes and Z-R singlets, and leads to the increase of free spins and the decrease of dimer spins. For Ca doped samples, the oxygen deficiency decreases with the increase of Ca content, but Ca doping enhances the transfer of holes from spin chains to spin ladders.