Eur. Phys. J. B 7, 9-17 (1999)
https://doi.org/10.1007/s100510050585

²⁷Al Nuclear Magnetic Resonance studies of CeAuAl₃

Laboratorium für Festkörperphysik, Eidgenössische Technische Hochschule-Hönggerberg, 8093 Zürich, Switzerland

Received: 5 May 1998
Revised: 16 July 1998
Accepted: 20 July 1998
Published online: 15 January 1999

Abstract

We report ²⁷Al Nuclear Magnetic Resonance studies of CeAuAl₃ and LaAuAl₃ at frequencies between 1.30 and 76.91 MHz and at temperatures from 45 mK up to 320 K. CeAuAl₃ is a new heavy-electron compound which orders antiferromagnetically at 1.32 K. For the two inequivalent Al sites of CeAuAl₃, the transferred hyperfine couplings and are relatively small compared to those in other Ce compounds. The nuclear quadrupolar coupling constants are 2.9 MHz and 7.8 MHz, respectively. We suggest that the magnetic structure of the ordered state below 1.32 K is of a simple spiral type with the ordered Ce moments arranged ferromagnetically within the (ab) planes of the tetragonal crystal lattice. Based on this magnetic structure we estimate a 25% reduction of the Ce moments, most likely due to Kondo screening. At high temperatures, in the paramagnetic state of CeAuAl₃, the spin-lattice relaxation rate is dominated by the fluctuations of the localised Ce moments. At 20 K, is , more than two orders of magnitude larger than for the reference compound LaAuAl₃. For temperatures lower than 20 K decreases as a function of (T/H) and below 1 K, displays a linear-in-T behaviour, strongly enhanced compared to the reference compound LaAuAl₃.