Experimental studies of weakly ferromagnetic ZrZn2

M. Uhlarz1, C. Pfleiderer1, H. v. Löhneysen1,2, S. M. Hayden3 und G. G. Lonzarich4
1Physikalisches Institut, Universität Karlsruhe
2Forschungszentrum Karlsruhe, Institut für Festkörperphysik
3University of Bristol, Bristol BS8 1TL, UK
4University of Cambridge, Cambridge CB3 0HE, UK

The weak itinerant ferromagnet ZrZn2 is believed to be the archetypal material for which the standard framework of the spin fluctuation model of itinerant magnetism provides a quantitatively correct description. Assuming the absence of interband transitions and drag effects, this model has recently acquired general interest for its use in describing non-Fermi liquid properties of heavy fermion systems at a magnetic quantum phase transition. Here we present new, detailed measurements of the pressure and magnetic field dependence of the magnetisation and resistivity of weakly ferromagnetic ZrZn2. However, the properties we observe are inconsistent with simple Landau damping of the spin fluctuations, expected for the high purity of the samples investigated, but are instead suggestive of diffusive spin fluctuation relaxation. We discuss the possible origin of these deviations in the light of the assumptions underlying the conventional framework of spin fluctuation theory.