High-temperature 63Cu(2) nuclear quadrupole and magnetic resonance measurements of YBa2Cu4O8

We report data on the Gaussian transverse relaxation rate 1/T2G, the Knight shift Ks, and the spin-lattice relaxation time T1, in YBa2Cu4O8 from 100 K up to 715 K, extending the upper temperature of previous studies by 200 K. The T2G data are corrected for a small spin-lattice fluctuation contribution to the echo decay. Calculations of T1T/T2G and T1T/T2G2 show that there is a crossover in scaling behavior at a temperature Tcr∼500 K. The …