Synthesis and characterization of thin film multiferroic

摘要

We have synthesized thin films of multiferroic Ni_3V_2O_8 by sputter deposition on several different substrates. X-ray diffraction and Raman spectroscopy confirm that the films are single phase Ni_3V_2O_8, with the as-deposited amorphous films developing an increasingly polycrystalline structure on annealing at 900 deg C. Films prepared on sapphire substrates have a pronounced b-axis orientation, with grain sizes approaching 10 mu m. The magnetization of the thin film samples exhibits an anomaly coincident with the transition to a canted antiferromagnetic state in bulk Ni_3V_2O_8. Preliminary dielectric investigations on these thin film samples show a subtle feature coincident with the magnetic ordering transition, which shows no dependence on bias voltage up to an electric field of 4MVm~(-1).