Spin gap and nuclear magnetic relaxations in the cuprate superconductors

Abstract

The differences between the magnetic properties in the normal state of the underdoped and optimally doped high- T c cuprates are discussed based on a phenomenological model, in which the effect of the spin gap on the magnetic susceptibility is included. The closely related temperature dependences of the uniform static spin susceptibility, the spin-lattice relaxation rate at the planar O sites 17( T 1 T) −1 and Cu sites 63( T 1 T) −1, and the ratio of 63( T 1 T) −1 to the squared Gaussian relaxation rate at the planar Cu sites T 2G −2 are considered. The theoretical predictions are in agreement with experiments.