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March Meeting Review

March Meeting Review. Huanlong Liu Dallas Tx , 2011. Spin torque study. Basic idea: Goals: Study spin transfer torque and field like torque (as a function of magnetization angle) in MTJs Methods: STT-FMR, Time resolved signals Presentations: V19.9: T. Moriyama et al. Cornell

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March Meeting Review

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  1. March Meeting Review Huanlong Liu Dallas Tx, 2011

  2. Spin torque study • Basic idea: • Goals: Study spin transfer torque and field like torque (as a function of magnetization angle) in MTJs • Methods: STT-FMR, Time resolved signals • Presentations: • V19.9: T. Moriyama et al. Cornell • V19.11: H. W. Tseng et al. Cornell • V19.13: C. Wang et al. Cornell

  3. V19.9 • Spin transfer torque in magnetic tunnel junctions with a perpendicularly magnetized polarizer • Sample Structure: V V [Co 0.2 / Ni 0.4]x 3 180 x 80 CoFeB 1.1 MgO 1 TMR = 31% f f CoFeB 1.1 [Co 0.25 / Ni 0.4]x 8 extended

  4. V19.11 • High Voltage Pulse Measurements of Microwave Emission and Spin-Torque effects in Magnetic Tunnel Junction • Main Idea: when voltage is high, field like torque will influence the switching phase diagram • Setup: P 0.8 V 0.9 V t Bias Tee Directional coupler

  5. V19.13 • Time-resolved detection of spin-transfer-driven ferromagnetic resonance and spin torque measurement in magnetic tunnel junctions • Chen Wang, Y-T, Cui, R.A. Buhrman, D.C. Ralph • Nature Physics DOI:10.1038/NPHYS1928 (2011)

  6. Setup

  7. Sample structure Circular: D = 80 nm / 90 nm RA = 1.5 Ωμm2 TMR = 85% ~ 100 % C < 5 x 10-14 F Happ = 200 ~450 Oe (in plane, 45° ~ 135°) • Sample # 1: • 90 nm x 90 nm • Rp = 272 Ω • TMR = 91% • Sample # 2: • 80 nm x 80 nm • Rp = 381 Ω • TMR = 97% Capping layer Ru(6)/Ta(3)/Ru(4) Free layer CoFe(0.5)/CoFeB(3.4) Tunnel barrier MgO(x) SAF IrMn(6.1)/CoFe(1.8)Ru/CoFeB(2.0) Bottom electrode Ta(3)/CuN(41.8)/Ta(3)/CuN(41.8)/Ta(3)/Ru(3.1)

  8. ST-FMR in the time domain Extrapolate:

  9. Determination of the STT From VSM measurement: From fitting ST-FRM data to a Kittel formula:

  10. Determination of the STT

  11. Determination of the STT

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