Asymmetric Voltage Behavior of the Tunnel Magnetoresistance in Double Barrier Magnetic Tunnel Junctions

In this paper, we study the value of the tunnel magnetoresistance (TMR) as a function of the applied voltage in double barrier magnetic tunnel junctions (DMTJs) with the left and right ferromagnetic (FM) layers being pinned and numerically estimate the possible difference of the TMR curves for negative and positive voltages in the homojunctions (equal barriers and electrodes). DMTJs are modeled as two single barrier junctions connected in series with consecutive tunneling (CST). We investigated the asymmetric voltage behavior of the TMR for the CST in the range of a general theoretical model. Significant asymmetries of the experimental curves, which arise due to different annealing regimes, are mostly explained by different heights of the tunnel barriers and asymmetries of spin polarizations in magnetic layers.

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Bias voltage effect on tunnel magnetoresistance in fully epitaxial MgO double-barrier magnetic tunnel junctions

Applied Physics Letters ◽

10.1063/1.1867559 ◽

2005 ◽

Vol 86 (8) ◽

pp. 082501 ◽

Cited By ~ 41

Author(s):

T. Nozaki ◽

A. Hirohata ◽

N. Tezuka ◽

S. Sugimoto ◽

K. Inomata

Keyword(s):

Bias Voltage ◽

Tunnel Junctions ◽

Magnetic Tunnel Junctions ◽

Double Barrier ◽

Tunnel Magnetoresistance

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Influence of annealing temperature and thickness of a CoFeB middle layer on the tunnel magnetoresistance of MgO based double barrier magnetic tunnel junctions

Journal of Applied Physics ◽

10.1063/1.3065521 ◽

2009 ◽

Vol 105 (1) ◽

pp. 014510 ◽

Cited By ~ 6

Author(s):

A. Reinartz ◽

J. Schmalhorst ◽

G. Reiss

Keyword(s):

Annealing Temperature ◽

Tunnel Junctions ◽

Magnetic Tunnel Junctions ◽

Middle Layer ◽

Double Barrier ◽

Tunnel Magnetoresistance

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Spin-Polarized Current in Spin Valves and Magnetic Tunnel Junctions

MRS Bulletin ◽

10.1557/mrs2006.99 ◽

2006 ◽

Vol 31 (5) ◽

pp. 389-394 ◽

Cited By ~ 39

Author(s):

Stuart Parkin

Keyword(s):

Room Temperature ◽

Tunnel Junctions ◽

Magnetic Tunnel Junctions ◽

Memory Storage ◽

Tunnel Barrier ◽

Tunnel Magnetoresistance ◽

Ferromagnetic Electrodes ◽

Diffusive Scattering ◽

Spin Polarized ◽

Tunnel Barriers

AbstractSpin-polarized currents can be generated by spin-dependent diffusive scattering in magnetic thin-film structures or by spin-dependent tunneling across ultrathin dielectrics sandwiched between magnetic electrodes.By manipulating the magnetic moments of the magnetic components of these spintronic materials, their resistance can be significantly changed, allowing the development of highly sensitive magnetic-field detectors or advanced magnetic memory storage elements.Whereas the magneto-resistance of useful devices based on spin-dependent diffusive scattering has hardly changed since its discovery nearly two decades ago, in the past five years there has been a remarkably rapid development in both the basic understanding of spin-dependent tunneling and the magnitude of useful tunnel magnetoresistance values.In particular, it is now evident that the magnitude of the spin polarization of tunneling currents in magnetic tunnel junctions not only is related to the spin-dependent electronic structure of the ferromagnetic electrodes but also is considerably influenced by the properties of the tunnel barrier and its interfaces with the magnetic electrodes.Whereas the maximum tunnel magnetoresistance of devices using amorphous alumina tunnel barriers and 3d transition-metal alloy ferromagnetic electrodes is about 70% at room temperature, using crystalline MgO tunnel barriers in otherwise the same structures gives tunnel magnetoresistance values of more than 350% at room temperature.

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