Affiliation:
1. Aptiv Services Poland S.A., Krakow 30-707, Poland and Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
Abstract
This article focuses on the spin-torque ferromagnetic resonance (STFMR) technique, which was developed and optimized to investigate spin-transfer effects in magnetic tunnel junctions (MTJ) and spin Hall effect phenomena in ferromagnet/non-magnetic heavy metal bilayer systems. The devices for STFMR are typically fabricated with co-planar waveguides with contact pads for applying radio frequency or direct current, Irf(Idc). The device under investigation was a CoFeB/MgO/CoFeB based MTJ with a resistance-area product of 1.5 Ω ( μm)2 having a circular cross section with a diameter of 180 nm and tunneling magneto-resistance in the range of 60%–80%. The development of the STFMR setup and its optimization for achieving higher signal-to-noise ratio (SNR) is discussed using two modulation schemes, namely, radio-frequency modulation and field modulation (FM). The FM-STFMR method reduces frequency-dependent noise and offers a higher SNR of 30 dB compared to other modulation schemes in the literature. In addition, a vector network analyzer based STFMR technique is developed, which provides a simple and fast means for characterizing MTJ devices. Furthermore, to calculate the exact power reaching the MTJ, impedance mismatch is calculated using the de-embedding method. The magnitude of in-plane torkance and out-of-plane torkance with dc bias is measured, and the results are found to be consistent with the results of STFMR techniques. The results show that the magnitude of out-of-plane torkance is substantially smaller than that of in-plane torkance in MTJ.
Funder
University Grants Commission
Cited by
1 articles.
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