Presentation Information
[16a-S4_201-6]Demonstration of field-free spin Hall nano-oscillators with an antiferromagnet/ferromagnet heterostructure
〇(B)Yuzu Yoshida1,2, Karunathilaka Vihanga De Zoysa1, Hitoshi Iida1,3, Aakanksha Sud1,4, Takaaki Dohi1, Akash Kumar1,5,6, Ahmad Awad1,5,6, Shun Kanai1,2,3,6,7,8,9, Hideo Ohno1,6,7,10, Johan Akerman1,5,6, Shunsuke Fukami1,2,3,6,7,10,11 (1.LNS, RIEC, Tohoku Univ., 2.Eng.,Tohoku Univ., 3.Dept. Electro. Eng., Tohoku Univ, 4.FRIS, Tohoku Univ., 5.Physics Department, Univ. of Gothenburg, 6.CSIS, Tohoku Univ., 7.WPI-AIMR Tohoku Univ., 8.DEFS, Tohoku Univ., 9.NIQST, 10.CIES Tohoku Univ., 11.InaRIS)
Keywords:
Exchange bias,field-free oscillation,Spin Hall nano-oscillators
Spin Hall nano-oscillators (SHNOs) have been investigated for the development of neuromorphic computing and Ising-machine applications; however, their operation generally requires an external magnetic field, which poses a challenge for device integration. In this study, we demonstrate field-free auto-oscillation in a nano-constriction-based SHNO by utilizing exchange bias in an antiferromagnet/ferromagnet heterostructure. Increasing the thickness of the antiferromagnetic PtMn layer enhances the exchange bias acting on the adjacent permalloy layer, which functions as an effective magnetic field replacing the external field. On the other hand, excessively thick PtMn layers reduce the effective spin Hall torque per applied current, thereby suppressing the onset of auto-oscillations. Consequently, stable field-free auto-oscillations are obtained in devices with an 11-nm-thick PtMn layer, where an exchange bias field of 10 mT is realized. These results indicate that antiferromagnet/ferromagnet heterostructures provide a viable approach for integrated SHNOs.