[19p-P1-1~74] 10 Spintronics and Magnetics（Poster）

▲ [19p-P1-72] Enhancement of emission power in vortex spin torque oscillator

〇Sumito Tsunegi¹, Kay Yakushiji¹, Hitoshi Kubota¹, Akio Fukushima¹, Shinji Yuasa¹ (1.AIST)

Keywords:Spin torque oscillator

Spin torque oscillator (STO) is a device which can transform dc signal to the radio frequency (rf) signal through the spin dynamics and magneto-resistance effect. Because the rf power of STO is proportional to the square of the magneto resistance (MR) ratio, improvement of MR ratio is the key to enhance the rf power of STO. It is well known that the MR ratio is evidently determined by selecting the combination of barrier and electrode materials. In our previous work, the combination of CoFeB/MgO/FeB was chosen, and the highest emission power was 3.6 μW in vortex-STO. In this work, we inserted CoFe to the FeB/MgO interface to further improvement of MR ratio and rf power of vortex-STO.
The CoFe insertion results in the improvement of MR ratio by a factor of 1.15. The improvement comes from the suppression of branches except for Δ₁ band in the coherent tunneling process. The highest value of rf power was 6.3μW in vortex-STO with CoFe insertion, which is almost 2 times larger than that without CoFe insertion. This is the highest rf power from STOs reported to date.