The tunnel magnetoresistance in chains of quantum dots weakly coupled to external leads

2009/12/08 by Ireneusz Weymann
Physics and Astronomy · #Condensed matter physics #Magnetic field #Magnetic properties of thin films #Magnetoresistance #Physics #Quantum #Quantum and electron transport phenomena #Quantum dot #Quantum mechanics #Semiconductor Quantum Structures and Devices #cond-mat.mes-hall

paper · pdf · doi:10.1088/0953-8984/22/1/015301

published as J. Phys.: Condens. Matter 22 015301 (2010) (11pp)

openalex publication_date 2009/12/08 · arxiv created 2009/12/10 · arxiv updated 2015/05/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We analyze numerically the spin-dependent transport through coherent chains of three coupled quantum dots weakly connected to external magnetic leads. In particular, using the diagrammatic technique on the Keldysh contour, we calculate the conductance, shot noise and tunnel magnetoresistance (TMR) in the sequential and cotunneling regimes. We show that transport characteristics greatly depend on the strength of the interdot Coulomb correlations, which determines the spatial distribution of the electron wavefunction in the chain. When the correlations are relatively strong, depending on the transport regime, we find both negative TMR as well as TMR enhanced above the Julliere value, accompanied with negative differential conductance (NDC) and super-Poissonian shot noise. This nontrivial behavior of tunnel magnetoresistance is associated with selection rules that govern tunneling processes and various high-spin states of the chain that are relevant for transport. For weak interdot correlations, on the other hand, the TMR is always positive and not larger than the Julliere TMR, although super-Poissonian shot noise and NDC can still be observed.

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