Electronic structure of Al 3 Ni and AlNi 3 alloys Zs. Kova ´ cs Department of Experimental Physics, Lajos Kossuth University, Debrecen, Bem te´r 18/a, Hungary L. Ko ¨ ve ´ r Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen, P.O. Box 51, Hungary P. Weightman Department of Physics and Interdisciplinary Research Center in Surface Science, University of Liverpool, P.O. Box 147, L69 3BX, United Kingdom D. Varga Institute of Nuclear Research of the Hungarian Academy of Sciences, H-4001 Debrecen, P.O. Box 51, Hungary R. Sanjine ´ s Institut de Physique Applique´e, Ecole Polytechnique Fe´de´rale, CH-1015 Lausanne, Switzerland J. Pa ´ linka ´ s Department of Experimental Physics, Lajos Kossuth University, Debrecen, Bem te´r 18/a, Hungary G. Margaritondo Institut de Physique Applique´e, Ecole Polytechnique Fe´de´rale, CH-1015 Lausanne, Switzerland H. Adachi Department of Materials Science and Engineering, Kyoto University, Yoshida-honmachi, Kyoto 606, Japan ~Received 27 September 1995; revised manuscript received 1 May 1996! Experimental Al KL 23 V and Ni LMM Auger and high-resolution valence band XPS spectra of Al 3 Ni and AlNi 3 alloys are presented and compared to the corresponding spectra of pure metals. The spectra are inter- preted in terms of the results of the discrete-variational ~DV!-X a cluster MO model using atomic Auger transition probabilities. Good agreement has been obtained between the theory and experiment concerning the energy widths of the spectra. For Al 3 Ni the total number of electrons at the Fermi level obtained from the calculations agrees better with the experimental value than those from previous calculations. In the case of the alloys, the calculated charge transfer is small ~,0.4 electrons!, playing only a minor role in the filling of the Ni d band. The hybridization between the Ni d and Al s and p bands can be deduced from the reduction of the Al s and p DOS at the Ni d resonance energy. Our results suggest that for these alloys the corresponding Auger matrix elements do not depend on the Auger transition energy. The Ni LMM spectra of the alloys demonstrate the localization of the Ni d band. @S0163-1829~96!04735-2# INTRODUCTION Studies of the effect of changes in the local electronic environment on atomic processes in components of alloys can make a valuable contribution to the understanding of electronic properties of these materials. For theories of alloy stability, the charge transfer is of special interest. Particularly interesting are the cases of the simple metal–transition metal ~TM! alloys, where a significant contribution to the filling of the d bands of the transition metal can come from hybridiza- tion and from charge transfer. 1,2 Effects of alloying can be observed clearly in dilute alloys, where an atom of one metal can be almost entirely surrounded by atoms of the other con- stituent. Ni is an interesting transition-metal component in such alloys because it is possible to change the Ni d band filling by alloying such that the number of unfilled states becomes zero. To study the hybridization between the d or- bitals of the TM and the s and p orbitals of the simple metal. Al is a good metal partner component, because, as in the case of MgNi 2 , 2 the expected hybridization effects are strong. The studies of the electronic structure of Al-Ni alloys allow us to obtain relevant information like the applicability of the final state rule 3 for the interpretation of the Al core-valence Auger line shapes, and the effect of the transition energy depen- dence of the Auger matrix elements on Al K Auger spectra. 4 The purpose of this paper is to present experimental Al KL 23 V , Ni LMM Auger and x-ray photoelectron spectra of Al 3 Ni and AlNi 3 alloy samples and to interpret the experi- mental spectra using a cluster-type molecular orbital model. From the core-valence Auger spectra, information can be obtained on the site-projected local density of electron states as well as on the role of the different excitation processes. The measured alloy and metal 4 Al KL 23 V Auger spectral shapes are compared to each other and with the theoretical PHYSICAL REVIEW B 15 SEPTEMBER 1996-II VOLUME 54, NUMBER 12 54 0163-1829/96/54~12!/8501~5!/$10.00 8501 © 1996 The American Physical Society