Sources of negative tunneling magnetoresistance in multilevel quantum dots with ferromagnetic contacts

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We analyze distinct sources of spin-dependent energy level shifts and their impact on the tunneling magnetoresistance (TMR) of interacting quantum dots coupled to collinearly polarized ferromagnetic leads. Level shifts due to virtual charge fluctuations can be quantitatively evaluated within a diagrammatic representation of our transport theory. The theory is valid for multilevel quantum dot systems and we exemplarily apply it to carbon nanotube quantum dots, where we show that the presence of many levels, among them of excited states, can qualitatively influence the TMR effect.
Original languageEnglish
Article number045313
JournalPhysical Review B Condensed Matter
Issue number4
Number of pages8
Publication statusPublished - 13 Jan 2012

ID: 36141484