Magnetic properties of bulk and thin film Cr–Al–C compounds

Abstract

A focus point in this work was the study of the magnetic properties of Cr–Al–C in both bulk and film form. The coatings, deposited by high power impulse magnetron sputtering, consisted of a mixture of disordered solid solution (Cr,Al)₂C _x and ordered Cr₂AlC-MAX phase (ternary alloy with general formula M _n+1AX _n : M = early transition metal, A = A group element, mostly IIIA or IVA, X = C or N, n = 1–3), while the bulk samples consisted of ordered Cr₂AlC-MAX phase. The magnetic properties of Cr–Al–C in both bulk and film form show paramagnetic behaviour with a combination of Curie–Weiss and Pauli dependence. In the film, the Curie–Weiss component dominates. From the fit parameters, it could be seen that the magnetisation on the Cr site is in a high spin state and that the difference between the bulk and film can be accounted for by the number of Cr sites carrying this magnetic moment. However, even in the film, the total magnetisation does not equate to every Cr site carrying this magnetic moment. The number of Cr sites has been linked to the amount of solid solution (Cr,Al)₂C _x within the material.