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Suppression of in-plane tunneling anisotropic magnetoresistance effect in Co2MnSi/MgO/n-GaAs and CoFe/MgO/n-GaAs junctions by inserting a MgO barrier

2011; American Institute of Physics; Volume: 98; Issue: 23 Linguagem: Inglês

10.1063/1.3595311

1520-8842

Takafumi Akiho, Tetsuya Uemura, Masanobu Harada, Ken-ichi Matsuda, Masafumi Yamamoto,

Magnetic and transport properties of perovskites and related materials

The effects of MgO tunnel barriers on both junction resistance and tunneling anisotropic magnetoresistance (TAMR) characteristics of Co2MnSi(CMS)/MgO/n-GaAs junctions and Co50Fe50(CoFe)/MgO/n-GaAs junctions were investigated. The resistance-area (RA) product of the CMS/MgO/n-GaAs junctions showed an exponential dependence on MgO thickness (tMgO), indicating that the MgO layer acts as a tunneling barrier. The RA product of CMS/MgO/n-GaAs with tMgO<1 nm was smaller than that of the sample without MgO. The observed spin-valvelike magnetoresistance of CMS/n-GaAs and CoFe/n-GaAs Schottky tunnel junctions attributed to the TAMR effect did not appear in the cases of CMS/MgO/n-GaAs and CoFe/MgO/n-GaAs tunnel junctions. The lowering of the RA product and the suppression of the TAMR effect caused by inserting a thin MgO layer between CMS and n-GaAs were both possibly due to suppression of the Fermi-level pinning of GaAs and lowering of the Schottky barrier height.