  The non-Fermi liquid system (NFL) YbCu_(5-x)Al_(x) (x = 1.3 - 1.75) has been
investigated in hetero- as well as homo-contact arrangement in magnetic fields
up to 22.5 T. The observed dV/dI(V) characteristics reveal asymmetry in
hetero-contact arrangement and do not agree with the model of thermal contact
heating, at least close to zero-bias voltage. In the case of a hetero-contact
arrangement we have observed a maximum at only one voltage polarity at about
1.3 mV (for x = 1.5), which asymmetry is suppressed in an applied magnetic
field. This behavior is connected with NFL properties of studied compounds.
