Phase diagram of YBa2Cu3O7-y at T < Tc according to transverse nuclear relaxation data for Cu(2)

Abstract

Two peaks are observed at T = 35 and 47 K in the transverse relaxation rate for Cu(2) nuclei in YBa2Cu3O7-y. A comparison of the relaxation rates for isotopes 63Cu(2) and 65Cu(2) at T= 47 K indicates the magnetic nature of relaxation. The enhancement of local magnetic field fluctuations perpendicular to CuO2 planes at T= 47 K is associated with critical fluctuations of orbital currents. The peak at T = 35 K is attributed to the emergence of an inhomogeneous superconducting phase. The obtained experimental results and the available data from the literature made it possible to propose a qualitatively new phase diagram of the superconducting state. © 2001 MAIK "Nauka/Interperiodica".