ANISOTROPY OF MICROCONTACT CHARACTERISTIC S OF URU2SI2 IN NORMAL-STATE

The differential resistance dV/dI(V) of the microcontacts made of a sy stem with heavy fermions (HFS) URu2Si2 has been measured in temperatur e range 1,5-20 K along Iso principal crystallographic directions. A di stinctive feature, of the dV/dI(V) measured in the HFS microcontacts a l the temperature below the Neel point T-N = 17.5 K is an asymmetrical ly-located peak with respect to zero voltage (V = 0). On the symmetric al portion of the dV/dI(V) curve of the homocontacts the above peak ha s been observed at the current flowing perpendicularly to the c-axis o f single crystal and is as a rule absent or suppressed when the curren t is c-axially directed. This peak is supposed to be associated with a n anisotropic energy gap arising from the spin density saves (SDW) and appearing (at temperature below T-N) on the part of the Fermi surface , !he ab plane of URu2Si2. The gap magnitude estimated from the width of the peak of the symmetric portion of the dV/dI(V) curve at V = 0 is turned to he equal 10 +/- 1 mV. A reproducible asymmetry of the diffe rential resistance has been investigated on the URu2Si2-to-ordinary me tal heterocontacts. This property is assumed tb be related to an influ ence of the peak in high density of electron states which is located a symmetrically relative to the Fermi level.