Characterization of interfacial properties in magnetic tunnel junctions by bias-dependent complex impedance spectroscopy

C. Y. Hsu, J. C.A. Huang

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

The bias-dependent complex impedance spectra of ion-beam sputtered CoFe-AlOx-CoFe tunnel junctions have been systematically investigated. An equivalent circuit model, composed of a resistance component and two sets of parallel resistance (R) and capacitance (C) components in series, has been utilized to describe the individual impedance contribution from lead of cross patterns, CoFe-AlOx interfaces and bulk AlO x in CoFe-AlOx-CoFe tunnel junctions. The fitting results reveal that the RC component characterizing the CoFe-AlOx interface can be explained by a Schottky barrier with imperfectly blocking characteristic, which is attributed to the existence of traps in the depletion region. The tendency of interfacial resistance, Ri, and interfacial capacitance, Ci, as a function of dc bias, Vdc, is expected for the space charge limited current model with exponential trap distribution, which coincides with the analyzing results of dc four-probe current-voltage curves. On the other hand, the R and C components of bulk AlOx almost remain constant when Vdc increases, in contrast to the electrical behavior of CoFe-AlOx interfaces. The results suggest the metal-insulator interface, instead of bulk insulator, dominates the electrical transport process of MTJs.

Original languageEnglish
Pages (from-to)3643-3645
Number of pages3
JournalIEEE Transactions on Magnetics
Volume41
Issue number10
DOIs
Publication statusPublished - 2005 Oct 1

Fingerprint

Tunnel junctions
tunnel junctions
Capacitance
Spectroscopy
impedance
Electric space charge
Equivalent circuits
Ion beams
spectroscopy
Lead
capacitance
Metals
insulators
traps
Electric potential
equivalent circuits
space charge
depletion
tendencies
ion beams

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

Cite this

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abstract = "The bias-dependent complex impedance spectra of ion-beam sputtered CoFe-AlOx-CoFe tunnel junctions have been systematically investigated. An equivalent circuit model, composed of a resistance component and two sets of parallel resistance (R) and capacitance (C) components in series, has been utilized to describe the individual impedance contribution from lead of cross patterns, CoFe-AlOx interfaces and bulk AlO x in CoFe-AlOx-CoFe tunnel junctions. The fitting results reveal that the RC component characterizing the CoFe-AlOx interface can be explained by a Schottky barrier with imperfectly blocking characteristic, which is attributed to the existence of traps in the depletion region. The tendency of interfacial resistance, Ri, and interfacial capacitance, Ci, as a function of dc bias, Vdc, is expected for the space charge limited current model with exponential trap distribution, which coincides with the analyzing results of dc four-probe current-voltage curves. On the other hand, the R and C components of bulk AlOx almost remain constant when Vdc increases, in contrast to the electrical behavior of CoFe-AlOx interfaces. The results suggest the metal-insulator interface, instead of bulk insulator, dominates the electrical transport process of MTJs.",
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Characterization of interfacial properties in magnetic tunnel junctions by bias-dependent complex impedance spectroscopy. / Hsu, C. Y.; Huang, J. C.A.

In: IEEE Transactions on Magnetics, Vol. 41, No. 10, 01.10.2005, p. 3643-3645.

Research output: Contribution to journalArticle

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