  Studies of sessile droplets and fluid bridges of a ferroelectric nematic
liquid crystal in externally applied electric fields are presented. It is found
that above a threshold, the interface of the fluid with air undergoes a
fingering instability or ramification, resembling to Rayleigh-type instability
observed in charged droplets in electric fields or circular drop-type
instabilities observed in ferromagnetic liquids in magnetic field. The
frequency dependence of the threshold voltage was determined in various
geometries. The nematic director and ferroelectric polarization direction was
found to point along the tip of the fingers that appear to repel each other,
indicating that the ferroelectric polarization is essentially parallel to the
director. The results are interpreted in connection to the Rayleigh and
circular drop-type instabilities.
