Journal of Alloys and Compounds 451 (2008) 457–460 Magnetism of the series of intermetallic Ce 5 CuM 3 compounds, where M = Sn, Pb and Bi V.H. Tran a,∗ , M. Gam˙ za b , A. ´ Slebarski b , W. Miiller a , J. Jarmulska a a W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw, Poland b Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice, Poland Available online 21 April 2007 Abstract We present a short summary of experimental and theoretical studies on the isostructural intermetallics Ce 5 CuM 3 (M = Sn, Pb and Bi), crystallizing in the hexagonal Hf 5 CuSn 3 -type structure (space group P6 3 /mcm). The investigated compounds are found to undergo multiple magnetic phase transitions at low temperatures. We discuss the role of f-spd hybridization on the evolution of heavy-fermion state across the series of the studied compounds. The band structure calculations not only support magnetic ground state of the studied compounds but also suggest an inequivalent contribution of Ce atoms at different positions to the density of states. © 2007 Elsevier B.V. All rights reserved. PACS: 71.27.+a; 71.20.Lp; 75.20.Hr; 75.30.−m Keywords: 4f-Intermetallics; Heavy fermion; Multiple magnetic phase transitions; f-spd hybridization 1. Introduction Investigation of magnetic properties of new series of Ce- based intermetallic compounds is one of the important tasks in the fields of strongly correlated electron systems. The potential of such a study for physics is to discover new physical phenom- ena as well as to establish a systematic trend in the magnetic behaviour of these intermetallics, and hopefully to determine at least main factors responsible for their magnetism. Recently, our attention has focused on the series Ce 5 CuM 3 , where M = Sn, Sb, Pb and Bi [1–4]. Except for Ce 5 CuSb 3 with an orthorhombic structure [2] the other compounds have found to crystallize in the hexagonal Hf 5 CuSn 3 -type structure [6–8]. From the magnetic point of view the studied compounds are of interest because the existing two different magnetic sublattices for the Ce ions in the unit cell may provide complicated magnetic structures. In fact it has been shown that these Ce 5 CuM 3 compounds undergo into several successive magnetic phase transitions at low tem- peratures [2–4]. However, the most remarkable finding of our studies is the observation of heavy-fermion (HF) characteristics which manifest them self by an enhancement in the electronic specific-heat coefficient of some Ce 5 CuM 3 compounds [1,2,4]. ∗ Corresponding author. Tel.: +48 71 3435021; fax: +48 71 3441029. E-mail address: v.h.tran@int.pan.wroc.pl (V.H. Tran). Generally for magnetic Ce-based intermetallics the formation of the HF state is believed to be the result of competition between the Kondo effect and long-range RKKY exchange interaction [5]. In this context the coexistence of the HF property and mag- netic ordering in Ce 5 CuM 3 series offers the possibility to study the effect of competing above mentioned interactions. The aim of the present paper is to give a short summary of the bulk data obtained sofar on Ce 5 CuM 3 with M = Sn, Pb and Bi, and to discuss the observed properties according to their electronic structures based on X-ray photoemission spectroscopy (XPS) studies and electronic band calculations. 2. Results and discussion For Ce 5 CuM 3 (M = Sn, Pb and Bi) we have measured magnetization (magnetic susceptibility), specific-heat, electri- cal resistivity, magnetoresistance, thermoelectric power and XPS spectra. Detail of experimental procedure has been given previously [1,3,4]. Some experimental data are illustrated in Figs. 1 and 2. The basis characteristics emerging from the mea- surements are gathered in Table 1. From these figures and the table we can deduce the following features: (i) Multiple magnetic transition of an antiferro/ferrimagnetic ground state is found at low temperatures. 0925-8388/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2007.04.227