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"Competing spin interactions as a new route to multiferroic materials"

Relatore: Prof. Michel Kenzelmann, ETHZ and PSI, Switzerland

Aula Maxwell
24 Febbraio 2005 ore 15.30

Strongly-correlated quantum spin systems with competing interactions can have a large number of degenerate ground state configurations with unusual spin fluctuations. Anisotropic interactions can then favor a subset of spin configurations and new ground states can emerge. I will talk about materials with competing spin interactions in which antiferromagnetic and ferroelectric order parameters are strongly coupled. The materials were characterized using macroscopic measurements and neutron diffraction/spectroscopy. Ferroelectricity seems to emerge as soon as the magnetic structure breaks the inversion symmetry of the crystal.