鑭鍶錳氧與白金鈀金雙層膜結構之自旋幫浦效應

Spin Pumping Effect in (La, Sr)MnO3 Capped with Pt or Pd

駱冠宇(Guan-Yu Luo)

指導教授 ： 林昭吟

共同指導教授 ： 張慶瑞

國立臺灣大學/理學院/物理學研究所/博士(2016年)

https://doi.org/10.6342/NTU201602452

摘要

無資料

關鍵字

自旋電子學

並列摘要

Ferromagnetic resonance (FMR) driven spin pumping is a novel method to transfer spin angular momentum from the ferromagnetic (FM) layer into the adjacent nonmagnetic metal (NM) layer in an FM/NM bilayer system. Consequently, the spin current can be probed in the NM layer via inverse
spin Hall effect (ISHE) when spin-charge conversion occurs. Although a scaling behavior of the ISHE voltage vs. FMR pumping angle was observed in various FM/Pt bilayers with FM being a Heusler alloy, ferromagnetic oxide spinel and dilute magnetic semiconductor, the influences of conductivity and the interface properties on the spin current density are still not well understood. Among many, Pt is considered as the most effective NM for spin-charge conversion due to its strong spin orbital coupling. In contrast with previous reports, we grow Pt and Pd on La0.7Sr0.3MnO3 (LSMO) and study the spin transport properties of these two systems. By fitting with the spin pumping model, the values of spin transport parameters are obtained, including the interface spin mixing conductance, the spin diffusion length of Pt(Pd) and spin Hall angle. The values for LSMO/Pt (LSMO/Pd) bilayer are 2.18×1019 m-2 (1.81×1019 m-2 ) for spin mixing conductance, 6.0 nm (7.6 nm) for spin diffusion length and 0.013 (0.004) for spin Hall angle. In particular, two models were used to calculate spin diffusion length and spin Hall angle, with and without spin current back flow. It is found that the value of spin Hall angle is sensitive to the model modification while the mixing conductance is not. This finding provides some insight to resolve the controversy of experimental results of spin Hall angle from different groups. Another finding is that the spin current densities of LSMO/Pt and LSMO/Pd are very close (~0.70 nJ/m2 at 40 mW) and comparable to that of Py/Pt, which makes LSMO a potential FM spin pump.

並列關鍵字

spintronics

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