Temperature dependence of the antiferromagnetic state inURu2Si2by point-contact spectroscopy

Point-contact spectroscopy has been used to study the temperature evolution of the spin-density-wave (SDW) behavior of a ${\mathrm{URu}}_2$ ${\mathrm{Si}}_2$ single crystal. In the c direction at a temperature of 19 K, we observe the onset of an asymmetric structure in the dV/dI versus V characteristic, and this has been correlated with the development of a SDW gap. We observe that the data follow a BCS behavior. In addition, we have performed tunneling experiments that indicate that only portions of the Fermi surface are being gapped. From these data we have measured the energy gap, 2Δ=11.7 meV, and the ratio 2Δ/${\mathit{K}}_{\mathit{B}}$ ${\mathit{T}}_{\mathit{N}}$ which gives a value of the order of 7.2.