Observation of spin-dependent quantum well resonant tunneling in textured CoFeB layers

We report the observation of spin-dependent quantum well (QW) resonant tunneling in textured CoFeB free layers of single MgO magnetic tunnel junctions (MTJs). The inelastic electron tunneling spectroscopy spectra clearly show the presence of resonant oscillations in the parallel configuration, which...

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Bibliographic Details
Published in:Applied physics letters 2014-03, Vol.104 (11)
Main Authors: Teixeira, J. M., Costa, J. D., Ventura, J., Sousa, J. B., Wisniowski, P., Freitas, P. P.
Format: Article
Language:English
Subjects:
Applied physics
Bias
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
Electric potential
ELECTRON SPECTROSCOPY
Electron tunneling
MAGNESIUM OXIDES
MAGNETORESISTANCE
Magnetoresistivity
MATHEMATICAL SOLUTIONS
Oscillations
QUANTUM WELLS
Resonant tunneling
Spectrum analysis
SPIN
THICKNESS
TUNNEL EFFECT
Tunnel junctions
Tunnel magnetoresistance
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Summary:We report the observation of spin-dependent quantum well (QW) resonant tunneling in textured CoFeB free layers of single MgO magnetic tunnel junctions (MTJs). The inelastic electron tunneling spectroscopy spectra clearly show the presence of resonant oscillations in the parallel configuration, which are related with the appearance of majority-spin Δ1 QW states in the CoFeB free layer. To gain a quantitative understanding, we calculated QW state positions in the voltage-thickness plane using the so-called phase accumulation model (PAM) and compared the PAM solutions with the experimental resonant voltages observed for a set of MTJs with different CoFeB free layer thicknesses (tfl = 1.55, 1.65, 1.95, and 3.0 nm). An overall good agreement between experiment and theory was obtained. An enhancement of the tunnel magnetoresistance with bias is observed in a bias voltage region corresponding to the resonant oscillations.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4869484