Backhopping effect in magnetic tunnel junctions: comparison between theory and experiment

Abstract

We report on the magnetic switching and backhopping effects due to spin-transfer-torque in magnetic tunnel junctions. Experimental data on the current-induced switching in junctions with MgO tunnel barrier reveal a random back-and-forth switching between the magnetization states, which appears when the current direction favors the parallel magnetic configuration. The effect depends on the barrier thickness $t_b$, and is not observed in tunnel junctions with very thin MgO tunnel barriers, $t_b$ $<$ 0.95 nm. Switching dependence on the 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 at high bias voltages in a non-deterministic switching behavior, 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.

7 pages, 3 figures, regular journal paper

References in corpus (2)

• Ab initio studies of the spin-transfer torque in tunnel junctions
• Influence of MgO tunnel barrier thickness on spin-transfer ferromagnetic resonance and torque in magnetic tunnel junctions

Cited by in corpus (5)

• Back-hopping in Spin-Transfer-Torque switching of perpendicularly magnetized tunnel junctions
• Back hopping in spin-transfer-torque devices, possible origin and counter measures
• Reduction of back switching by large damping ferromagnetic material
• Switching based Spin Transfer Torque Oscillator with zero-bias field and large tuning-ratio
• Ultrafast and low-energy switching in voltage-controlled elliptical pMTJ