Shape anisotropy effects on spin-torque oscillators

Spin-torque oscillators are promising candidates for hard disk drive read head sensors, neuromorphic computing, and telecommunications due to their frequency tunability by a direct current or a magnetic field. A narrow linewidth and a large quality factor are of great importance for these applications. Previous studies have indicated that the spin-torque oscillation linewidth depends on the temperature, current, and in-plane field angle. Here, we have investigated the spin-torque oscillations in MgO-based magnetic tunnel junctions (MTJs) and demonstrated the impact of the MTJ shape anisotropy on the threshold current. Our experimental results suggest that due to different threshold currents, the linewidth is different in the MTJs with different shape anisotropy, which might be significant for device optimization.