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Spin polarization of (Ga,Mn)As measured by Andreev spectroscopy: The role of spin-active scattering

S. Piano, R. Grein, C. J. Mellor, K. Výborný, R. Campion, M. Wang, M. Eschrig, and B. L. Gallagher
Phys. Rev. B 83, 081305(R) – Published 15 February 2011

Abstract

We investigate the spin polarization of the ferromagnetic semiconductor (Ga,Mn)As by point-contact Andreev reflection spectroscopy. The conductance spectra are analyzed using a recent theoretical model that accounts for momentum- and spin-dependent scattering at the interface. This allows us to fit the data without resorting, as in the case of the standard spin-dependent Blonder-Tinkham-Klapwijk (BTK) model, to an effective temperature or a statistical distribution of superconducting gaps. We find a transport polarization PC57%, in considerably better agreement with the k⃗·p⃗ kinetic-exchange model of (Ga,Mn)As, than the significantly larger estimates inferred from the BTK model. The temperature dependence of the conductance spectra is fully analyzed.

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  • Received 25 January 2011

DOI:https://doi.org/10.1103/PhysRevB.83.081305

©2011 American Physical Society

Authors & Affiliations

S. Piano1, R. Grein2, C. J. Mellor1, K. Výborný3, R. Campion1, M. Wang1, M. Eschrig2,4,5, and B. L. Gallagher1

  • 1School of Physics and Astronomy, University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom
  • 2Institut für Theoretische Festköperphysik and DFG-Center for Functional Nanostructures, Karlsruhe Institute of Technology, D-76128 Karlsruhe, Germany
  • 3Institute of Physics ASCR, v.v.i., Cukrovarnická 10, Praha 6, CZ-16253, Czech Republic
  • 4Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany
  • 5SEPnet and Hubbard Theory Consortium, Department of Physics, Royal Holloway, University of London, Egham, Surrey TW20 0EX, United Kingdom

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Issue

Vol. 83, Iss. 8 — 15 February 2011

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