Multiferroic Order at a Single Phase Transition

Gavin Lawes

Department of Physics & Astronomy

Wayne State University

Multiferroic materials with co-existing magnetism and ferroelectricity offer the opportunity to study spin-charge coupling in materials. Systems developing ferroelectric and magnetic orders simultaneously at a single phase transition are particularly interesting because of the intimate coupling of the order parameters in these materials. I will discuss some experimental work on several single-transition multiferroics, including TbMnO₃, Ni₃V₂O₈, and Ba_.5Sr_1.5Zn₂Fe₁₂O₂₂, in which the spontaneous polarization can be controlled using an external magnetic field. I will discuss a model for magnetically induced ferrolectric order in the context of a recently identified system that undergoes a multiferroic transition directly from a disordered state. I will conclude by presenting some preliminary results on thin film single transition multiferroic materials.