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Magnetoresistance of a quantum dot with spin-active interfaces

Audrey Cottet·Mahn-Soo Choi
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Abstract

We study the zero-bias magnetoresistance MR of an interacting quantum dot connected to two ferromagnetic leads and capacitively coupled to a gate voltage source Vg. We investigate the effects of the spin-activity of the contacts between the dot and the leads by introducing an effective exchange field in an Anderson model. This spin-activity makes easier negative MR effects, and can even lead to a giant MR effect with a sign tunable with Vg. Assuming a twofold orbital degeneracy, our approach allows to interpret in an interacting picture the MR(Vg) measured by S. Sahoo et al. [Nature Phys. 2, 99 (2005)] in single wall carbon nanotubes with ferromagnetic contacts. If this experiment is repeated on a larger Vg-range, we expect that the MR(Vg) oscillations are not regular like in the presently available data, due to Coulomb interactions.

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Audrey Cottet, Mahn-Soo Choi. 2006-10-12. Magnetoresistance of a quantum dot with spin-active interfaces. https://doi.org/10.1103/physrevb.74.235316

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