Effect of pinholes in magnetic tunnel junctions

Xi Chen, R. H. Victora

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The electron transport in magnetic tunnel junction containing pinholes is studied, where ferromagnetic layers make direct contact through narrow conducting channels. The transport is treated within the Landauer formalism using a tight-binding Hamiltonian. It is found that a narrow pinhole induces a resonant tunneling behavior causing a magnetoresistance that oscillates with the bias voltage. After averaging over pinholes of various shapes, the oscillation and magnitude of magnetoresistance (MR) are reduced, which can explain how barrier roughness diminishes the MR. For a pinhole of a large radius, where the number of atoms inside is much larger than 1, an enhanced MR is obtained whose value is similar to an all-metal giant magnetoresistance spin valve.

Original languageEnglish (US)
Article number212104
JournalApplied Physics Letters
Issue number21
StatePublished - 2007

Bibliographical note

Funding Information:
We thank Ed Murdock for useful discussion. This work was supported by the National Science Foundation under Award No. ECS-0621868 and by the University of Minnesota Supercomputing Institute.


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