Dresden 2011 – wissenschaftliches Programm
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KR: Fachgruppe Kristallographie
KR 5: Poster Multiferroics (Joint Session of MA, DF, DS, KR, TT)
KR 5.39: Poster
Dienstag, 15. März 2011, 10:45–13:00, P2
Scaling study on magnetic ordering transition and specific heat in the cubic helimagnet FeGe — •Andrey A. Leonov1, Michael Baenitz2, Walter Schnelle2, Marcus Schmidt2, Ulrich K. Rössler1, and Heribert Wilhelm3 — 1IFW Dresden, P.O. Box 270116, D-01171 Dresden, Germany — 2MPI CPfS, Noethnitzer Str. 40, 01187 Dresden — 3Diamond Light Source Ltd., Chilton, Didcot, OX11 0DE, United Kingdom
The magnetic phase transition of the cubic helimagnet FeGe at the ferromagnetic-paramagnetic transition have been analyzed from a scaling study on dc magnetization data by extrapolation from high applied fields. The critical properties have been calculated for a hypothetical homogeneously magnetized state, as FeGe is a helimagnet in the zero-field state. The exponents β for spontaneous magnetization, γ for the initial susceptibility above TC, and δ for the critical magnetization isotherm at TC have been obtained from modified Arrott plots and by the Kouvel-Fisher method. The analysis indicates a conventional magnetic phase transition with critical exponents similar to those expected for an isotropic magnet belonging to the Heisenberg universality class. Deviations from the ferromagnetic ordering are discernible at low applied fields for T < TC owing to the onset of chiral twisting and the inception of helimagnetic order. The specific heat data display only a small region near TC where scaling applies and reliable determination of the related exponent α is not possible. The anomalous specific heat closer to TC indicates a first-order phase transition.