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.
Bibliographical noteFunding Information:
This work was supported by Seagate Technology and National Science Foundation through the MRSEC Program under Award No. DMR-0819885. We thank Dr. Wonjoon Jung, Dr. Jae-Young Yi, Dr. Eric W. Singleton, and Dr. Mark Kief for useful discussions and suggestions. We gratefully acknowledge Professor Randall H. Victora and Dr. Tao Qu for their help on the micromagnetic simulations, which are not included in this manuscript.
This work was supported by Seagate Technology and National Science Foundation through the MRSEC Program under Award No. DMR-0819885.*%blankline%*