Regensburg 2016 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 5: Spin Textures and magnetic Phase Transitions

MA 5.2: Vortrag

Montag, 7. März 2016, 10:15–10:30, H34

Four-ion magnetic coupling in the heavy rare earth elements — •Eduardo Mendive Tapia and Julie Staunton — Department of Physics, University of Warwick, Coventry CV4 7AL, U.K.

The study of the magnetic properties of the heavy rare earth elements has attracted much attention owing to the complexity of their magnetic order. A complex series of magnetic phases, spanning antiferromagnetic (AF) helical, conical helical and fan phases and also ferromagnetic states is formed as the temperature and applied magnetic field are varied. The AF phases are usually incommensurate with the underlying hexagonal close packed lattice. The origin of these magnetic structures derives from the indirect interaction of the local moments, formed from localized 4f states, which is mediated by the conduction electrons. Here we employ an ab-initio Disordered Local Moment (DLM) theory to investigate the magnetic phase transitions. The orientations of thermally fluctuating 'local moments' associated with the 4f electrons are considered to vary slowly on the scale of the faster itinerant conduction electronic motions which in turn drive the indirect interactions between the local moments. We focus on the study of transitions that are characteristic of the common valence electronic structure among the heavy rare earth elements. As a main result, we identify an isotropic four-ion magnetic coupling, emerging from the nature of the conduction electronic structure, as the decisive driving factor for the temperature and field evolution of the magnetic ordering.