Critical magnetic fluctuations in localized and itinerant magnets studied by neutron scattering [Elektronische Ressource] / Daniel Lamago Kaffo

Critical Magnetic Fluctuations inLocalized and Itinerant MagnetsStudied by Neutron ScatteringDipl. Phys. Univ. Daniel Lamago KaffoVollstandiger¨ Abdruck der von der Fakultat¨ fur¨ Physik der TechnischenUniversitat¨ Munchen¨ zur Erlangung des akademischen Grades einesDoktor der Naturwissenschaften (Dr. rer. nat.)genehmigten Dissertation.Vorsitzender: Univ. Prof. Dr. Manfred Kleber¨ ¨Prufer der Dissertation: 1. Univ. Prof. Dr. Peter Boni2. Univ Dr. Winfried PetryDie Dissertation wurde am 04.04.2006 an der Technischen Universitat¨ Munchen¨eingereicht und durch die Fakultat¨ fur¨ Physik am 25.04.2006 angenommen.Dedicated toLaurick Moriel, Shirel Hodiya and He´le`ne.AbstractCritical magnetic fluctuations in localized and itinerant magnets have been studied bymeans of bulk methods and small angle scattering of polarized neutrons. The effect ofthree and four spin correlations corresponding to the dynamical and spontaneous chiral ity, respectively, on the critical behavior is discussed.Results of spin fluctuations in the critical temperature range of the Heisenberg ferromag net EuS are presented. We used the inclined magnetic field geometry in SANS experimentto induce the chirality in EuS and thus determine the three spin correlation function. Twocontributions to the critical scattering were studied close to T = 16.5 K.