NMR investigations in copper-oxide chain compounds and high-T(C) superconductors
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We report 89Y nuclear magnetic resonance measurements of the chain compound Ca2+xY2−xCu5O10. It is believed that this compound undergoes an antiferromagnetic 3D ordering transition at low temperatures for small doping concentrations of x ≈ 0, while for higher dopings it exhibits a quasi-1D chain behavior, and finally transitions to cluster behavior for doping levels close to x = 2. We present measurements of the spin-lattice and the spin-spin relaxation times T1 and T2, respectively, at several different temperatures for x = 0 and x = 0.5. Information for the spin correlation times in the studied system was extracted from the relaxation rates. In addition, a measurement of the lineshape was made for the x = 0.5 sample. As a preparation for the experiment, modifications in the original design of the NMR probe were made which significantly improved its functionality and eased the data acquisition process. The 160 MHz intermediate frequency NMR spectrometer was rebuilt and its operation was tested by performing NMR on several reference samples.