XPS and thermomagnetic characterization of the CeNi4Cr compound

The magnetic, thermodynamic and electronic structure properties are discussed for the CeNi₄Cr compound. The X-ray photoemission spectra (XPS) provide an evidence of a mixed valence behavior with the occupancy of the f states n_f=0.89 and their hybridization with the conduction electrons Δ=30 meV. These values reproduce well the magnetic susceptibility χ(T=0), which is enhanced compared to similar CeNi₄M (M=Al, B, Cu) compounds. In combination with a slightly increased electronic specific heat coefficient (up to 100 mJ mol⁻¹ K⁻²), this compound can be classified as being on the border of the heavy fermion and mixed valence behavior. Using a small magnetic field in the χ(T) measurements reveals a presence of magnetically ordered impurity phase, which is easily damped by higher fields and it is shown that the contribution of this phase is minor. The question of the dependence of the electronic specific heat coefficient on the magnetic field is also addressed and the observations agree well with theoretical predictions based on the Anderson model.