On tunnel spectroscopy of normal metals with charge- or spin-density waves

Current-voltage (I-V) characteristics of the tunnel current J across symmetrical and nonsymmetrical tunnel junctions, which use for plates metals with charge- or spin-density waves and the dielectric gap Σ on the Fermi surface sections, are calculated. For the symmetrical (s) junction the I-V characteristic is antisymmetrical about a bias V and does not depend on the sign of Σ. The dependence Js(V) involves the square root singularity for eV = Σ and the infection for eV = 2 Σ. The I-V characteristic of the nonsymmetrical (ns) junction depends on the sign of Σ. Different terms in Jns(V) have different symmetry properties with respect to the replacement V →-V. As a whole, for both types of tunnel junctions the results differ essentially from the well-known ones for the BCS superconductors. There is a qualitative agreement with the scanning tunneling microscopy measurements for layered dichalcogenides and point-contact spectroscopy measurements for the compound U Ru2 Si2. The explanation of the linear dependence of conductance G on the bias V in the oxide metal junctions is put forward