Paper MI+2D-WeM13
Spin Transport in NiO Measured with Ferromagnetic Resonance

Wednesday, October 23, 2019, 12:00 pm, Room A210

Recently, a measured spin diffusion length of approximately 22 nm was reported for spin current transmission through polycrystalline NiO.¹ The diffusion length is inferred by referencing the effective Gilbert damping constant in NiO/Fe₂₀Ni₈₀ bilayers as a function of NiO and Fe₂₀Ni₈₀ thickness. We present results using a different approach to determine the spin diffusion length, using trilayers of Fe₂₀Ni₈₀/NiO/Pt with FMR measurements covering the frequency range of 4 GHz to 50 GHz. The Pt serves as a spin sink when deposited directly on Fe₂₀Ni₈₀ and strongly increases the effective damping parameter. With NiO between the Pt spin sink and the ferromagnetic Fe₂₀Ni₈₀, the increase in damping parameter is diminished, and the decay length is extracted from measurements as a function of NiO thickness. Our preliminary measurements show that the decay length is smaller than 15 nm consistent with a decay length of approximately 4 nm determined from inverse spin hall effect measurements of Y₃Fe₅O₁₂/NiO/Pt structures.² In addition, at lower FMR frequencies (4 GHz as compared to 22 GHz) multiple resonances are observed for polycrystalline NiO, suggesting that ferromagnetic impurities are present in the antiferromagnet.

Results for polycrystalline and epitaxial trilayers will be presented, showing the effect of processing conditions on the spin diffusion length. These measurements will be correlated with microstructural and morphological characterization of the samples.

References

1 Tetsuya Ikebuchi, Takahiro Moriyama, Hayato Mizuno, Kent Oda, and Teruo Ono, Appl Phys Express 11 (7), 073003 (2018).

2 Yu-Ming Hung, Christian Hahn, Houchen Chang, Mingzhong Wu, Hendrik Ohldag, and Andrew D. Kent, AIP Advances 7 (5), 055903 (2017).