NMR pressure study ofAl27andCu65in theAl65Cu20Ru15quasicrystal

The isotropic Knight shift (${\mathit{K}}_{\mathrm{iso}}$) and nuclear spin-lattice relaxation rate (${\mathit{R}}_1$) of ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ and ${}_{}{}^{65}{}_{}{}^{}\mathrm{Cu}$ were studied at 77 K in the ${\mathrm{Al}}_{65}$ ${\mathrm{Cu}}_{20}$ ${\mathrm{Ru}}_{15}$ I-phase as functions of pressure. Up to 1.8 kbar the ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ ${\mathit{K}}_{\mathrm{iso}}$ values showed no deviation from the room pressure value (0.032±0.003)%, and up to 1.9 kbar the ${\mathit{R}}_1$ values changed by no more than 20% of the values at 1 bar for both ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ and ${}_{}{}^{65}{}_{}{}^{}\mathrm{Cu}$. These results and previous temperature and composition dependence NMR data are not consistent with a factor of 2 change in the s-band electronic density of states over an energy scale of ${10}^{\mathrm{-}2}$ eV.