Theoretical Study of Spin-dependent Electron Transport in Atomic Fe Nanocontacts

Abstract

We present theoretical predictions of spintronic transport phenomena that should be observable in ferromagnetic Fe nanocontacts bridged by chains of Fe atoms. We develop appropriate model Hamiltonians based on semi-empirical considerations and the known electronic structure of bulk Fe derived from ab initio density functional calculations. Our model is shown to provide a satisfactory description of the surface properties of Fe nano-clusters as well as bulk properties. Lippmann-Schwinger and Green's function techniques are used together with Landauer theory to predict the current, magneto-resistance, and spin polarization of the current in Fe nanocontacts bridged by atomic chains under applied bias. Unusual device characteristics are predicted including negative magneto-resistance and spin polarization of the current, as well as spin polarization of the current for anti-parallel magnetization of the Fe nanocontacts under moderate applied bias. We explore the effects that stretching the atomic chain has on the magneto-resistance and spin polarization and predict a cross-over regime in which the spin polarization of the current for parallel magnetization of the contacts switches from negative to positive. We find resonant transmission due to dangling bond formation on tip atoms as the chain is stretched through its breaking point to play an important role in spin-dependent transport in this regime. The physical mechanisms underlying the predicted phenomena are discussed.

13 pages, 6 figures, Accepted for publication in Physical Review B

References in corpus (9)

• Spintronics: Fundamentals and applications
• Spin-dependent transport in molecular tunnel junctions
• Electron Transport Through Molecules: Self-consistent and Non-self-consistent Approaches
• Absence of magnetically-induced fractional quantization in atomic contacts
• Magnetic and orbital blocking in Ni nanocontacts
• Ballistic magnetoresistance in nickel single-atom conductors
• The electrostatic potential profile along a biased molecular wire: A model quantum mechanical calculation
• Asymmetric I-V characteristics and magnetoresistance in magnetic point contacts
• Magnetoresistance of atomic-sized contacts: an ab-initio study

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