Robust mutual synchronization of long spin Hall nano-oscillator chains

Mutual synchronization of spin Hall nano-oscillators (SHNOs)¹ in chains² and 2D arrays³ can increase the signal quality an order of magnitude and be used for neuromorphic computing and Ising Machines^4,5. Here, we explore mutual synchronization in long SHNO chains of both NiFe(4 nm)/Pt(5 nm) and W(5 mm)/CoFeB(1.4 nm)/MgO(2 nm) and demonstrate robust synchronization of up to 21 SHNOs. A 300 kHz linewidth (for NiFe/Pt) and very high quality factors (Q=f/△f) of >30,000 for NiFe/Pt and >25000 for W/CoFeB/MgO are the best reported numbers for SHNO chains. Their wide frequency tunability (2-28 GHz)⁶ with current and magnetic fields along with their large non-linearity, make these oscillators ideal candidates for various spintronic applications.

 

References:

1. T. Chen et al., Proc. IEEE 104, 1919 (2016)

2. A. A. Awad et al., Nat. Phys. 13, 292 (2017).

3. M. Zahedinejad et al., Nat. Nano. 15, 47 (2020)

4. D. I. Albertsson et al., Appl. Phys. Lett. 118, 112404 (2021)

5. A. Houshang et al., arXiv:2006.02236.

6. M. Zahedinejad et al., Appl. Phys. Lett. 112, 132404 (2018)