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Wednesday, July 31

Using Inelastic Spectra to Determine the Spin States of Multiferroic Materials

Randy S. Fishman, Materials Science and Technology Division, ORNL
Materials and Chemistry Seminar Series
10:00 AM — 11:00 AM, Building 4500-N, Weinberg Auditorium
Contact: Adrian Sabau (sabaua@ornl.gov), 865.241.5145

Abstract

Because they couple magnetic and electric degrees of freedom, multiferroic materials hold tremendous technological promise and remain the center of intense scrutiny. In practice, elastic neutron scattering alone is insufficient to determine the complex, non-collinear spin structures of these materials. But the inelastic scattering spectrum provides a dynamical "fingerprint" for the spin state and interactions of multiferroic materials. This is demonstrated for two materials that fall within different classes of multiferroics. Whereas BiFeO3 is a "proper" multiferroic with the ferroelectric transition temperature Tc higher then the Neel transition temperature TN, CuFeO2 is an "improper" multiferroic with Tc = TN. Although the spin states of both materials are distorted cycloids, there are important differences between the two due to the different origins of their multiferroic behavior.