Coherent Electron-Correlation Compatible with Random Atom Stacking in Amorphous Ce–Ru Alloys

Abstract

The amorphous Ce–Ru alloys produced by the sputtering technique show the following distinct behaviors at low temperatures. The electronic specific heat coefficient rapidly increases below 5 K for Ce–19 and 42 at.%Ru alloys with decreasing temperature, T , (a heavy fermion behavior). The electrical resistivity displays -log T dependence at T >40 K (an incoherent or impurity Kondo effect). It slightly decreases at T <30 K for Ce–19 and 42 at.%Ru alloys (a coherent Kondo effect), while it abruptly decreases at 2.5 K for 82 at.%Ru (a superconducting phenomenon). These coherent states may originate from the strong mixing and correlation of 4f-electrons and conduction-electrons even in the random alloy system.