Shot noise in Co/Al2O3〈M〉/Py (M=Cr, Si) magnetic tunnel junctions
| Autor: | Ruben Guerrero, Jagadeesh S. Moodera, Tiffany S. Santos, Farkhad G. Aliev |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Fano factor
Materials science Condensed matter physics Scattering Doping Shot noise Coulomb blockade Condensed Matter::Mesoscopic Systems and Quantum Hall Effect Condensed Matter Physics Electronic Optical and Magnetic Materials Tunnel magnetoresistance Ferromagnetism Condensed Matter::Superconductivity Quantum tunnelling |
| Zdroj: | Journal of Magnetism and Magnetic Materials. 316:e990-e993 |
| ISSN: | 0304-8853 |
| DOI: | 10.1016/j.jmmm.2007.03.166 |
| Popis: | Low-frequency noise, including 1/ f and shot noise (SN), and dynamic tunneling resistance have been studied in Co (80 A)/Al 2 O 3 (14 A)/Py (100 A) magnetic tunnel junctions (MTJs) without doping and with Cr or Si δ-doping of the insulating barrier. The fluctuations in voltage were measured at frequencies (200 f 100 kΩ) tunneling resistances, the Fano factor shows “full” SN corresponding to uncorrelated tunneling ( F =1). The SN is reduced for the intermediate resistances with F ≈0.65–0.8 indicating correlated electron tunneling, most probably through the localized states formed by the defects inside the barrier. The SN is enhanced for the antiparallel alignment of the ferromagnetic electrodes in the MTJs with tunneling weakly affected by spin-flip scattering. A model, which considers trap-assisted sequential tunneling, qualitatively explains the main experimental results. Cr-doped MTJs typically showed Fano factor close to unity, probably due to some growth condition-induced asymmetry in Cr distribution. Incorporation of a Si δ-layer permits observation of an enhancement of the low-frequency noise, probably induced by Coulomb blockade effects. |
| Databáze: | OpenAIRE |
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