Non-stoichiometry and Antiferromagnetic Phase Transition of NaCl-type CrN Thin Films Prepared by Reactive Sputtering

• Published in: Materials Transactions, JIM Vol. 37; no. 2; pp. 121 - 129
• Main Authors: Tsuchiya, Yasuaki, Kosuge, Koji, Ikeda, Yasukuni, Shigematsu, Toshihiko, Yamaguchi, Sadaei, Nakayama, Noriaki
• Format: Journal Article
• Language: English
• Published: Sendai The Japan Institute of Metals 1996; Japan Institute of Metals
• Subjects: antiferromagnetic phase transition; chromium nitride; Composition and phase identification; Condensed matter: structure, mechanical and thermal properties; electrical resistivity; Exact sciences and technology; non-stoichiometry; Physics; reactive sputtering; Rutherford back scattering spectrometry; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; thin films; X-ray diffraction; X-ray photoelectron spectroscopy; RBS; Inorganic compounds; Chromium nitrides; Metastable phases; Phase transformations; Transition element compounds; Binary compounds; XRD; Experimental study; Lattice parameters; Photoelectron spectroscopy; Nonstoichiometry; Magnetic transition; Thin films; Magnetrons; NaCl structure; X radiation; Reactive sputtering; Electric conductivity
• ISSN: 0916-1821; 2432-471X
• DOI: 10.2320/matertrans1989.37.121

Non-stoichiometric CrN1+x (0.0≤x≤0.2) thin films with a NaCl-type structure have been prepared by reactive sputtering of chromium metal target in Ar/N2 mixed gas. Nearly stoichiometric CrN thin films are obtained at the N2 mixing ratio of 20% and the total pressure of 0.67 Pa. Magnetic susceptibility, electrical resistivity and X-ray diffraction measurements indicate that these films show an antiferromagnetic first order phase transition at around 260 K. With the increase in N2 partial pressure, metastable over-stoichiometric CrN1+x thin films are obtained. The compositions of samples prepared in pure N2 gas are almost CrN1.2 and the lattice constant is 2% greater than that of the nearly-stoichiometric bulk CrN. Over-stoichiometric CrN1+x thin films do not show the first order antiferromagnetic phase transition. Their χ-T curves show a broad maximum at around 90 K. The electrical resistivity at room temperature decreases with increasing the nitrogen composition and the temperature coefficient of resistivity is always negative. The composition dependence of magnetic and electrical properties correlates to the variation in the density of state near the Fermi level detected by XPS.