  We present measurements of the specific heat coefficient \gamma(= C/T) in the
low temperature limit as a function of an applied magnetic field for the
Fe-based superconductor BaFe$_2$(As$_{0.7}$P$_{0.3}$)$_2$. We find both a
linear regime at higher fields and a limiting square root $H$ behavior at very
low fields. The crossover from a Volovik-like $\sqrt{H}$ to a linear field
dependence can be understood from a multiband calculation in the quasiclassical
approximation assuming gaps with different momentum dependence on the hole- and
electron-like Fermi surface sheets.
