Formation of doped Al2O3 tunnel barriers by plasma oxidation of δ-doped Al

Jansen, R.; Davis, B.; Tanaka, C. T.; Moodera, Jagadeesh S.

doi:10.1016/s0039-6028(00)00560-4

Cited by 5 publications

(2 citation statements)

References 16 publications

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“…The quality of the Al layers and the Al 2 O 3 has been previously tested in Ref. [24,25]. In the following the positive bias voltage corresponds to the application of the voltage in the top electrode, while the negative to application of the voltage in the bottom one.…”

Section: Methodsmentioning

confidence: 99%

Conductance in Co/Al2O3/Si/Al2O3 permalloy with asymmetrically doped barrier

Guerrero,

Aliev,

Villar

et al. 2010

Preprint

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We report on dependence of conductance and tunnelling magnetoresistance on bias voltage at different temperatures down to 2K in Co|Al2O3(10Å)|Si(δ)|Al2O3(2Å)|Permalloy magnetic tunnel junctions. Complementary low frequency noise measurements are used to understand the conductance results. The obtained data indicate the breakdown of the Coulomb blockade for thickness of the asymmetric silicon layer exceeding 1.2Å. The crossover in the conductance, the dependence of the tunnelling magnetoresistance with the bias voltage and the noise below 80K correspond to 1 monolayer coverage. Interestingly, the zero bias magnetoresistance remains nearly unaffected by the presence of the silicon layer. The proposed model uses Larkin-Matveev approximation of tunnelling through a single impurity layer generalized to 3D case and takes into account the variation of the barrier shape with the bias voltage. The main difference is the localization of all the impurity levels within a single atomic layer. In the high thickness case, up to 1.8Å, we have introduced a phenomenological parameter, which reflects the number of single levels on the total density of silicon atoms.

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Section: Methodsmentioning

confidence: 99%

Conductance in Co/Al2O3/Si/Al2O3 permalloy with asymmetrically doped barrier

Guerrero,

Aliev,

Villar

et al. 2010

Preprint

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“…28,30) It was shown that the TMR decreases as a function of the impurity content of the Al 2 O 3 tunnel barrier, and that magnetic dopants reduce the TMR due to inelastic spin-exchange scattering of the tunneling electrons. 28) In the specific case of Ni in Al 2 O 3 , it was shown 31) that the Ni impurities are completely oxidized and incorporated as Ni ions (such as Ni 2+ and Ni 3+ ) in the tunnel barrier, providing the magnetic moments that facilitate spin-exchange scattering with the tunneling electrons. We suggest that a similar scenario is likely responsible for the decay of the Hanle spin signals due to Mn doping observed in this work.…”

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confidence: 99%

Suppression of spin transport in ferromagnet/oxide/semiconductor junctions by magnetic impurities in the tunnel barrier

Spiesser¹,

Saito²,

Yuasa³

et al. 2016

Appl. Phys. Express

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We have studied how the insertion of sub-monolayer amounts of Mn impurities in the middle of the oxide tunnel barrier of Fe/GeO2 on p-type Ge affects the spin transport, using three-terminal Hanle measurements. Strikingly, the magnitude of the Hanle spin voltage is strongly reduced by increasing the amount of Mn dopants and is even completely absent for devices having an amount of Mn impurities equivalent to a 0.2-nm-thick layer. This demonstrates that magnetic impurities in the tunnel barrier are detrimental to the spin transport in ferromagnet/oxide/semiconductor junctions, and that the localized states associated with such magnetic impurities do not produce three-terminal Hanle spin signals.

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