Superconducting Fluctuation Effects on the Spin-Lattice Relaxation Rate in ${\mathrm{YBa}}_2{\mathrm{Cu}}_3{O}_{6.95}$

We report ${}^{63}\mathrm{Cu}\left(2\right)$ spin-lattice relaxation rate measurements of ${\mathrm{YBa}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{6.95}$ in magnetic fields from 2.1 to 27.3 T obtained from ${}^{17}\mathrm{O}\left(2,3\right)$ nuclear magnetic resonance spin-spin relaxation. For $T<\mathrm{}120\mathrm{}\mathrm{K}$, the spin-lattice rate increases with increasing magnetic field. We identify this magnetic field dependence with the change in the low-energy spectral weight originating from $d$-wave pairing fluctuation corrections to the density of states.