Theory of tunneling spectroscopy of normal metal/ferromagnet/spin-triplet superconductor junctions

We study the tunneling conductance of a ballistic normal metal/ferromagnet/spin-triplet superconductor junction using the extended Blonder-Tinkham-Klapwijk formalism as a model for a $c$-axis-oriented Au/${\mathrm{SrRuO}}₃\text{/}{\mathrm{Sr}}₂{\mathrm{RuO}}₄$ junction. We compare chiral $p$-wave (CPW) and helical $p$-wave (HPW) pair potentials, combined with ferromagnet magnetization directions parallel and perpendicular to the interface. For fixed ${\ensuremath{\theta}}_M$, where ${\ensuremath{\theta}}_M$ is a direction of magnetization in the ferromagnet measured from the $c$ axis, the tunneling conductances of CPW and HPW clearly show different voltage dependencies. It is found that the cases where the $d$ vector is perpendicular to the magnetization direction (CPW with ${\ensuremath{\theta}}_M=\ensuremath{\pi}/2$ and HPW with ${\ensuremath{\theta}}_M=0$) are identical. The obtained results serve as a guide to determine the pairing symmetry of the spin-triplet superconductor ${\mathrm{Sr}}₂{\mathrm{RuO}}₄$.