Magnetic excitations and c-f hybridization effect in PrTi2Al20 and PrV2Al20

By means of Al-27 NMR studies, we have investigated magnetic excitations and the hybridization effect between Pr 4f and conduction electrons in a pair of cubic compounds PrTr2Al20 (Tr = Ti, V). From Knight shift measurements we have evaluated comparative strengths for the c-f hybridization effect in these compounds and confirm a definite increase of hybridization on replacing Ti with V. Analysis of the spin-lattice relaxation rate 1/T-1 reveals that the spectral width of magnetic fluctuations in crystalline electric field excited states is strongly temperature dependent. This result indicates that magnetic fluctuations are dominated by strong c-f exchange coupling at high temperatures and thus is nicely consistent with the Kondo picture that features ln T dependence of resistivity over the same temperature region.