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Stability of magnetic polarons in magnetic semiconductor single electron transistors: The effect of Coulomb interaction and external magnetic field
Author(s) -
Lebedeva N.,
Varpula A.,
Novikov S.,
Kuivalainen P.
Publication year - 2012
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201248030
Subject(s) - condensed matter physics , coulomb blockade , polaron , magnetic field , magnetic semiconductor , ferromagnetism , spin (aerodynamics) , curie temperature , electron , quantum dot , coulomb , physics , chemistry , transistor , voltage , optoelectronics , quantum mechanics , thermodynamics
In a magnetic single electron transistor (SET), which consists of a magnetic quantum dot (QD) coupled electrically to nonmagnetic source, drain, and gate electrodes, a magnetic polaron (MP) formation may occur, that is, the charge carrier spin may spin‐polarize the magnetic atoms of the QD and simultaneously the carrier becomes more tightly bound to the QD. We have studied theoretically the effect of the Coulomb interaction and magnetic field on the stability of the MPs in ferromagnetic SETs in the Coulomb blockade regime. The calculated results show that the temperature range, where MP is stable can be controlled by the gate voltage of the SET. At temperatures below the Curie temperature the stability decreases with magnetic field, whereas at higher temperatures the opposite is true. The Coulomb repulsion between two charge carriers separates the spin‐up and spin‐down energy levels, which stabilizes the MP further.