Spin-dependent thermoelectric effects in transport through a nanoscopic junction involving a spin impurity

Conventional and spin-related thermoelectric effects in transport through a magnetic tunnel junction with a large-spin impurity, such as a magnetic molecule or atom, embedded into the corresponding barrier are studied theoretically in the linear-response regime. The impurity is described by the gian...

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Bibliographic Details
Published in:Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2014-06, Vol.89 (23), Article 235438
Main Authors: Misiorny, Maciej, Barnaś, Józef
Format: Article
Language:English
Subjects:
Condensed matter
Exchange
Heat exchangers
Impurities
Magnetic anisotropy
Thermoelectricity
Transport
Tunnel junctions
Tunneling
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Summary:Conventional and spin-related thermoelectric effects in transport through a magnetic tunnel junction with a large-spin impurity, such as a magnetic molecule or atom, embedded into the corresponding barrier are studied theoretically in the linear-response regime. The impurity is described by the giant spin Hamiltonian, with both uniaxial and transverse magnetic anisotropy taken into account. Owing to the presence of the transverse component of magnetic anisotropy, the spin of a tunneling electron can be reversed during scattering on the impurity, even in the low-temperature regime. This reversal appears due to the exchange interaction of tunneling electrons with the magnetic impurity. We calculate Seebeck and spin Seebeck coefficients, and analyze their dependence on various parameters of the spin impurity and tunnel junction. In addition, conventional and spin figures of merit as well as the electronic contribution to heat conductance are considered. We also show that pure spin current can be driven by a spin bias applied to the junction with spin impurity, even if no electron transfer between the electrodes can take place. The underlying mechanism employs single-electrode tunneling processes (electrode-spin exchange interaction) and the impurity as an intermediate reservoir of angular momentum.
ISSN:1098-0121
1550-235X
DOI:10.1103/PhysRevB.89.235438