Suppression of asymmetric differential resistance in the non-Fermi-liquid system YbCu₅₋ₓAlₓ (x=1.3-1.75) in high magnetic fields

Abstract

The non-Fermi-liquid system YbCu5−xAlx (x=1.3-1.75) has been investigated in heterocontact as well as homocontact arrangement in magnetic fields up to 22.5 T. The observed differential resistance [dV/dI(V)] characteristics reveal asymmetry in heterocontact arrangement and do not agree with the model of thermal contact heating, at least close to zero-bias voltage. In the case of a heterocontact arrangement we have observed a maximum at only one voltage polarity at about 1.3 mV (for x=1.5) and this asymmetry is suppressed in an applied magnetic field. We show that such behavior is connected with the non-Fermi-liquid state of the studied system.