Impact of nitrogen on the charge-to-spin conversion efficiency in antiferromagnetic Mn3PtN compared to Mn3Pt thin films

The bilayer structures consisting of ${\mathrm{Mn}}_{3}\mathrm{PtN}$ (5 nm)/CoFeB(3 nm) and ${\mathrm{Mn}}_{3}\mathrm{Pt}$(5 nm)/CoFeB(3 nm) were fabricated via magnetron sputtering to investigate the role of nitrogen on charge-to-spin conversion efficiency in the noncollinear antiferromagnets (AFMs). The crystal structure of ${\mathrm{Mn}}_{3}\mathrm{PtN}$ (MPN) without N is consistent with that of ${\mathrm{Mn}}_{3}\mathrm{Pt}$ (MP) with $L{1}_{2}$-ordered structure, which allows us to study the different charge-to-spin conversion efficiency for AFMs with and without N. The spin-torque ferromagnetic resonance and second-harmonic Hall measurements were performed for both samples. It was revealed that the spin Hall angle $({\ensuremath{\theta}}_{\mathrm{SH}})$ of the MPN with spin polarization in the $y$ direction was observed to be \ensuremath{\sim}0.033, exceeding the corresponding value of MP (\ensuremath{\sim}0.025), which was qualitatively supported by the first-principles calculation. These results led us to conclude that N plays a crucial role in stabilizing the noncolliear antiferromagnetic structure and creating an electronic state advantage for the enhanced ${\ensuremath{\theta}}_{\mathrm{SH}}$.