Synthesis and characterization of thin film Ni$_3$V$_2$O$_8$

We have prepared thin films of multiferroic Ni$_3$V$_2$O$_8$ using sputter deposition and spin coating techniques. Raman spectroscopy and XRD confirm that the as-deposited films are amorphous, single-phase Ni$_3$V$_2 $O$_8$. These films develop increasing crystalline order on annealing at 900 $^ {\circ}$C, although they remain polycrystalline. These thin film Ni$_3$V$_2$O$_8$ samples develop a net magnetization below T=4 K; this temperature is consistent with the transition to a canted antiferromagnetic state in bulk samples. We observe an anomaly in the dielectric constant coincident with this magnetic transition. Despite being able to apply an electric field of over 6 MV/m to these samples, we are unable to observe any voltage-induced shift in this anomaly. We will discuss the implications of these results for future studies on thin film multiferroics.