Journal of magnetism and magnetic materials 9 (1978) 54-56 0 North-Holland Publishing Company zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA THE DYNAMICAL SUSCEPTIBILITY OF UAlz * S. HORN II. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Physik. Institut der Universit& KC%, K&I, Fed. Rep. Germany M. LOEWENHAUPT Institut ffir Festkiirperforschung der KFA Jiilich, Jiilich, Fed. Rep. Germany F. STEGLICH II. Physik. Institut der Universitiit Kijln, Kc%, Fed. Rep. Germany and W. JUST ILL, Grenoble, France Received 21 April 1978 We have performed diffuse neutron scattering experiments on UAlz in the temperature range between 2 K and 300 K. We found that the energy spectrum of the scattered neutrons is partly of magnetic origin. This magnetic part can be fitted by one quasielastic line. Its intensity is in good agreement with the static susceptibility and the half line width is surprisingly larger than kgT in the whole temperature range. 1. Introduction The nature of the Sf-electrons in the metallic actinide systems is not completely clear yet. Hill [l] was the first to look at the properties of uranium inter- metallic compounds in relation to the U-U separation a~__~. He found that for au-u < 3.5 A there is some- times superconductivity, but never magnetic order; for au_u > 3.5 A there is often magnetic order but never superconductivity. From that fact, it seems reasonable to conclude [2], that for au_u < 3.5 A there is direct overlap of the Sf-wave functions and therefore a description by a Sf-band is useful, while for a~__~ > 3.5 A a description by localized Sf-states is adequate. In accordance with this classification, UAl? with UU_U = 3.35 A should be described by a Sf-band. This is supported by macroscopic measure- * Work partly supported by SFB 125 Aachen-Jiilich-Kiiln. ments, e.g. susceptibility [3], resistivity [3] and spe- cific heat [4]. In this paper, we present the results of neutron scattering experiments in order to obtain more information about this compound from its dynamical susceptibility. We will find this quantity to behave similarly to the canonical intermediate valence rare earth compounds such as CePd, [5], which can be conveniently interpreted in terms of local models [6]. 2. Experiment and results The measurements were performed using the diffuse scattering apparatus D7 at the HFR Grenoble with neutrons of incident energy 3.53 meV in the tempera- ture range 2 K to 300 K. The energy of the scattered neutrons was analyzed by a time-of-flight (TOF) method. Absolute intensities were obtained by calibra- tion with a vanadium standard. The TOF-resolution 54