1 / 12

Compact Modeling of MTJs for use in STT-MRAM

Progress Update. Compact Modeling of MTJs for use in STT-MRAM. Richard Dorrance Advisor: Prof. Dejan Marković March 12, 2010. Motivation. Magnetic Tunnel Junctions (MTJs) exhibit magnetic hysteresis Excellent potential as memory Integratable with CMOS Non-volatile

ralph
Download Presentation

Compact Modeling of MTJs for use in STT-MRAM

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Progress Update Compact Modeling of MTJs for use in STT-MRAM Richard DorranceAdvisor: Prof. Dejan Marković March 12, 2010

  2. Motivation • Magnetic Tunnel Junctions (MTJs)exhibit magnetic hysteresis • Excellent potential as memory • Integratable with CMOS • Non-volatile • Spin-Transfer-Torque (STT) is a recently discovered phenomena • Predicted in 1996, observed in 2000 • No good compact model currently exists • Existing models oversimplify and ignore critical nonlinearities (temperature and voltage) • Problem for simulating STT-MRAM

  3. STT-MRAM

  4. Basic MTJ Structure

  5. Spintronic Operation • Spin Injector/Polarizer • Ferromagnetic layers tend to spin-polarize a current • Spin Detector • Ferromagnetic layers tend to scatter anti-parallel currents

  6. Compact Model Landau–Lifshitz–Gilbert Equation Julliere’s Conductance Model

  7. Temperature Nonlinearities • Saturation Magnetization • Weiss theory of ferromagnetism • Spin-Polarization • Affects resistance and STT • Modeled by:

  8. Voltage Nonlinearities • TMR changes for an applied bias voltage • Simple fitting function

  9. Simulation Setup • Compare transient behavior of MTJ model with a commercially available Micromagnetic Simulator: • ±1 mA, 10 ns pulses (30 ns total) • Total simulation time: • Micromagnetic Simulator: 13.5 hours • Verilog-A Model: 0.750 seconds

  10. Simulation Results b(θ) not implemented

  11. Future Work • Validation/refinement of model to measured devices • Explore the use of fitted function to replace b(θ) • b(θ) currently model a simple 5-layer structure • MTJ have 20+ layers with synthetic ferromagnets • Model C-STT 3rd Magnetic Layer (Perpendicular) • easier to switch • switching has greater thermal independence

  12. References [1] J. C. Slonczewski, J. Magn. Magn. Mater., vol. 159, pp. L1 – L7, 1996. [2] A. Raghunathan, et al., Magnetics, IEEE Trans., vol. 45, pp. 3954–3957, Oct. 2009. [3] C. H. Shang, et al., Phys. Rev. B, vol. 58, pp. R2917–R2920, Aug 1998. [4] Y. Lu, et al., J. Appl. Phys. vol. 83, no. 11. AIP, 1998, pp. 6515–6517. [5] X. Kou, et al., Applied Physics Letters, vol. 88, no. 21, p. 212115, 2006. [6] P. Wiśniowski, et al., Physica Status Solidi, vol. 201, pp. 1648–1652, 2004. [7] P. Padhan, et al., Applied Physics Letters, vol. 90, no. 14, p. 142105, 2007.

More Related