Non-Fermi-liquid behavior of YbCu5-xAlx

Abstract

A valency change in YbCu5−xAlx from ν≈2.2(x=0) to ν=3(x=2) causes a magnetic instability near a critical concentration xcr≈1.5. Alloys in the vicinity of xcr exhibit typical non-Fermi-liquid properties like a negative logarithmic contribution to the specific heat or substantial deviations of the electrical resistivity from a T2 behavior. Both pressure and alloying in this series bring about a strong reduction of the Kondo temperature TK; the crystal-field interaction and the interatomic exchange gain therefore importance and magnetic order becomes possible beyond xcr.