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Title: Backhopping effect in magnetic tunnel junctions: Comparison between theory and experiment

We report on magnetic switching and backhopping effects due to spin-transfer-torque in magnetic tunnel junctions. Experimental data on current-induced switching in junctions with a MgO tunnel barrier reveal random back-and-forth switching between magnetization states, which appears when the current direction favors the parallel magnetic configuration. The effect depends on the barrier thickness t{sub b} and is not observed in tunnel junctions with very thin MgO tunnel barriers, t{sub b} < 0.95 nm. The switching dependence on bias voltage and barrier thickness is explained in terms of the macrospin model, with the magnetization dynamics described by the modified Landau-Lifshitz-Gilbert equation. Numerical simulations indicate that the competition between in-plane and out-of-plane torque components can result in a non-deterministic switching behavior at high bias voltages, in agreement with experimental observations. When the barrier thickness is reduced, the overall coupling between the magnetic layers across the barrier becomes ferromagnetic, which suppresses the backhopping effect.
Authors:
; ;  [1] ;  [2] ;  [3] ;  [2] ;  [4] ;  [5] ;  [6]
  1. AGH University of Science and Technology, Department of Electronics, Al. Mickiewicza 30, 30-059 Krakow (Poland)
  2. Faculty of Physics, Warsaw University of Technology, Ul. Koszykowa 75, 00-662 Warsaw (Poland)
  3. (Poland)
  4. Institute of Molecular Physics, Polish Academy of Sciences, Ul. Smoluchowskiego 17, 60-179 Poznań (Poland)
  5. Thin Films and Physics of Nanostructures, Bielefeld University, 33615 Bielefeld (Germany)
  6. NanoSpin, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto (Finland)
Publication Date:
OSTI Identifier:
22266125
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 114; Journal Issue: 23; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; COMPUTERIZED SIMULATION; CONNECTORS; DIFFUSION BARRIERS; ELECTRIC CONTACTS; ELECTRIC POTENTIAL; MAGNESIUM OXIDES; MAGNETIZATION; PROGRAMMING LANGUAGES; SEMICONDUCTOR JUNCTIONS; SPIN; SUPERCONDUCTING JUNCTIONS; THICKNESS; TORQUE; TUNNEL EFFECT; TUNNELS; VENTILATION BARRIERS