講演情報
[21p-C501-9]Self-induced current trap of spin torque oscillation
〇Takahiko Makiuchi1, Naoki Kanazawa2, Eiji Saitoh1,3,4 (1.Univ. Tokyo, 2.IBM Quantum, 3.BAI, Univ. Tokyo, 4.AIMR, Tohoku Univ.)
キーワード：
spintronics、spin torque oscillator、microwave
Direct spin current into a ferromagnetic metal generates a nonlinear magnetization oscillation due to the spin-transfer torque. We report self-trapping and anti-trapping of such magnetization dynamics by the local inductive field in nano-gap spin Hall nano-oscillators. In a platinum (Pt) and permalloy (Py) bilayer, a charge current flowing through the heavy metal Pt layer induces both the spin-torque and local inductive field in the ferromagnetic Py layer. The spatial profile of the local field drastically changes by reversing the stacking order of Py and Pt. We fabricated Py/Pt (Py on Pt) and Pt/Py devices and performed experiments. The results show that the Py/Pt device has a smaller threshold current and higher quality factor, indicating better coherence. In our numerical micromagnetic simulations, the spatial profile of the magnetic oscillation is stable in the Py/Pt device. In contrast, it decays by emitting spin waves in the Pt/Py device. Both the linewidth and the threshold current are smaller in the Py/Pt case, supporting the observations.