L Journal of Alloys and Compounds 297 (2000) 53–58 www.elsevier.com / locate / jallcom Electronic structure, magnetic and electrical properties of Fe V Al 3 2x x compounds a, a a a a b * W. Zarek , E. Talik , J. Heimann , M. Kulpa , A. Winiarska , M. Neumann a Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice, Poland b ¨ ¨ ¨ Fachbereich Physics, Universitat Osnabruck, 49069 Osnabruck, Germany Received 21 July 1999; accepted 13 September 1999 Abstract The electronic band structure, magnetic and transport properties of monocrystalline Fe V Al compounds with the B2-type structure 32x x were investigated. It was found that the magnetic and unusual transport properties are due to a strong hybridization of the 3d states of iron and vanadium and their shift to below the Fermi energy.  2000 Published by Elsevier Science S.A. All rights reserved. Keywords: Fe Al; V substitution; Magnetic properties; Electrical resistivity; Electronic properties 3 1. Introduction Fe V Al compounds with the A2 and B2-type struc- 32x x ture. The intermetallic compounds Fe V Al, depending on 32x x the vanadium concentration and thermal or mechanical treatment, can exhibit the atomically ordered cubic struc- 2. Experimental tures DO (fcc), L2 (fcc) or B2 (sc) or exhibit the 3 1 atomically disordered of A2-type structure (bcc) [1–3]. Polycrystalline Fe V Al compounds with x#1.5 and 32x x The magnetic properties of these compounds markedly A2 or B2 structure were obtained by arc-melting of the depend on the degree of atomic order of the crystal stoichiometric quantities of Fe, V and Al in an argon structure [1–4]. The replacement of Fe atoms in Fe Al by atmosphere and annealing between 900–1000 K for a few 3 vanadium atoms causes strong reduction of the Curie days to obtain the B2-type structure. temperature and magnetic moment. The long-range mag- The single crystals of Fe V Al compounds for x50, 32x x netic order in these compounds disappears for x.0.9 0.5, 0.75, 0.85, 1 and 1.5 were obtained by the Czochralski [1–4]. The Fe V Al compounds with the DO -type method from a levitated melt using high purity starting 32x x 3 structure exhibit an anomalous temperature dependence of materials [6]. The quality of the single crystals was the electrical resistivity, characterised by a resistivity checked by the X-ray Berg–Barrette topography (Figs. 1 maximum near the Curie temperature and a negative and 2). The Laue and rotating crystal methods were used temperature coefficient of resistivity. The Fe VAl com- to establish orientation of the crystals and their lattice 2 pound exhibits semiconductor behaviour. The specific heat parameters. measurements suggest that this compound is a candidate The magnetic measurements of the investigated com- for the heavy-fermion system [5]. pounds were performed in the temperature range 77–1000 In this work we present result of the investigations of K in magnetic fields up to 1.2 T using the Faraday method. the crystal structure, magnetic properties, electrical resis- The electrical resistivity was measured by a convention- tivity and band structure for poly- and monocrystalline al method using 100 mA DC current in the temperature range 4.2–300 K. The XPS spectra of the Fe V Al single crystals, pure 32x x Fe and V were obtained with monochromatized Al Ka *Corresponding author. Tel.: 148-32-588-211; fax: 148-32-588-431. radiation at room temperature using PHI 5700 / 660 Phys- 0925-8388 / 00 / $ – see front matter  2000 Published by Elsevier Science S.A. All rights reserved. PII: S0925-8388(99)00610-6