Note on the Spin-Spin Relaxation Time in High-T_cCuprate Superconductors

Abstract

Recent experiments on the spin-spin relaxation time in high-Tc cuprate superconductors are discussed on the basis of the BCS-RPA theory.Keywords: spin-spin relaxation time, high-Tc cuprate superconductorThe temperature dependence of the spin-spin relaxation time recently measured in high-T c cuprate superconductors [2][3][4][5] deviates from the expected behavior of a prevailing thoery.[6] The observed relaxation time has strong temperature dependence for temperatures below the superconducting transition temparature, T < T c , while the theory predicts little temparature dependence. Such a temperature independence predicted by the theory was regarded as an evidence for the d-wave superconductivity and established by the measurements in La-and Y-systems. [7] On the other hand, the measurements in Tl-, Hg-and Bi-systems [2-5] revealed the insufficiency of the theory. [6] In this Short Note we clarify that the temperature independence is not a direct consequence of the theory by searching much wider parameter space than in the original work [6] and that the recent experiments [2-5] can be understood within the framework of the theory.The Gaussian component of the spin-spin relaxation time T