Evidence for gradual evolution of low-energy fluctuations underlying the first-order structural and valence order in YbPd
Abstract
The valence orders at Ta=125 K and Tb=105 K in the cubic compound YbPd have been investigated by 105Pd-nuclear magnetic resonance (NMR) measurements. Significant decrease in the density of states at the Fermi energy below Ta is evident from the measurement of nuclear spin lattice relaxation rate 1/T1, suggesting that the instabilities of Fermi surface are associated with the transitions. Moreover we observed the unusual evolution of low-energy fluctuations toward the valence transition at Ta behind its drastic first-order nature. The structural transition accompanying the valence order may occur as a result of cooperative effect of Fermi surface and valence instabilities.
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