Title: Point-contact spectroscopy of superconducting energy gap in $\rm DyNi_2B_2C$,
Abstract: The superconducting energy gap in $\rm DyNi_2B_2C$ has been investigated
using a point-contact technique based on the Andreev reflection from a normal
(N)-superconductor (S) boundary, where N is Ag. The observed differential
resistance $dV/dI$ is well described by the Blonder-Tinkham-Klapwijk (BTK)
theory based on the BSC density of states with zero broadening parameter.
Typically, the intensity of the gap structure amounts to several percentage of
the normal state resistance, which is an order of magnitude less than predicted
by the theory. For $\rm DyNi_2B_2C$ with $T_c<T_N$ (the Neel temperature), we
found gap values satisfying the ratio of $2\Delta_0/k_BT_c=3.63\pm 0.05$
similar to other superconducting nickel-borocarbides, both nonmagnetic and
magnetic with $T_c\geq T_N$. The superconducting gap nonlinearity is
superimposed on the antiferromagnetic structure in $dV/dI(V)$ which is
suppressed at the magnetic field of the order of 3T applied nominally in the
$ab$-plane and temperature $\geq 11~K$. The observed superconducting properties
depend on the exact composition and structure at the surface of the crystal.