Berlin 2015 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 20: POSTER Ib
MA 20.44: Poster
Dienstag, 17. März 2015, 09:30–13:00, Poster A
Field and temperature dependence of spin fluctuations in ZrZn2 — •Pascal Reiss, Gilbert Lonzarich, and F Malte Grosche — Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom
ZrZn2 is a low temperature band ferromagnet (Tc ≈ 28 K), which displays non-Fermi liquid transport properties over a wide temperature range: above TFL ≈ 1 K and even beyond Tc, the electrical resistivity follows a power-law temperature dependence with an exponent 5/3, whereas the electronic contribution to the thermal resistivity is linear in temperature. This has been explained in terms of a magnetic fluctuation model, which includes a self-consistent renormalisation for the magnetic susceptibility [1, 2]. Applied magnetic fields up to 9 T have been observed to increase the cross-over temperature TFL to ≈ 7 K. Previous calculations did not include effects of magnetic fields.
We will present the results of an extended calculation which accounts for the role of applied field, allowing a comparison between high field resistivity measurements and the predictions of a magnetic fluctuation model. Furthermore we will show that the magnetic transition is expected to be continuous in this model. However this transition is characterised by a strongly temperature dependent coefficient b(T) of the quartic term in a Landau-Ginzburg expansion. Moreover, b(T) changes sign at Tc, with b(T) < 0 in the ordered phase.
[1] G. G. Lonzarich and L. Taillefer, J Phys C: Solid State Phys, 18, 4339-4371 (1985)
[2] R. Smith et al., Nature, 455, 1220-1223 (2008)