Temperature dependence of the anisotropy of the planar oxygen nuclear spin-lattice relaxation rate in YBa2Cu3Oy
نویسندگان
چکیده
We report measurements of the full planar O nuclear spin-lattice relaxation rate tensor in optimally and underdoped YBa 2Cu 3O y (y56.96 and 6.63). The anisotropy varies strongly with temperature in both samples: for the y56.63 sample, the ratio of the relaxation rate measured with the applied field in the ab plane and oriented parallel to the copper-oxygen bond axis to that measured with the applied field in the ab plane and oriented perpendicular to the bond axis changes by over 25% from room temperature to Tc . The consequences of these results for theoretical models are discussed. They suggest that a second spin degree of freedom independent of the Cu~3d x22y2) – O(2ps) band exists in the CuO 2 planes of YBa 2Cu 3O y . @S0163-1829~98!04018-1#
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