  We derive a Ginzburg-Landau free energy for a p-wave ferromagnetic
superconductor. The starting point is a microscopic Hamiltonian including a
spin generalised BCS term and a Heisenberg exchange term. We find that
coexistence of magnetisation and superconductivity depends on the sign of the
energy-gradient of the DOS at Fermi level. We also compute the tunneling
contribution to the Ginzburg-Landau free energy, and find expressions for the
spin-currents and Josephson currents across a tunneling junction separating two
ferromagnetic p-wave superconductors.
