NMR study of Si-substitution effect for Al in PrTi _2 Al _20

We present the results of ^27 Al-nuclear magnetic resonance (NMR) studies of Si-substituted PrTi _2 Al _20 in order to clarify the magnetic and electronic properties at low temperatures and the change by Si substitution for Al from a microscopic point of view. From the analyses of the Knight shift, the hyperfine coupling constants on ^27 Al in PrTi _2 (Si _0.1 Al _0.9 ) _20 are slightly larger than those of PrTi _2 Al _20 . The nuclear spin-lattice relaxation rate 1/T_1 does not exhibit any anomaly around 2.0 K, in contrast to the results associated with the quadrupolar ordering in PrTi _2 Al _20 . The analysis of 1/T_1 at high temperatures reveals that the c – f hybridization may be reduced by Si substitution for Al.