Spin blockade in the conduction of colloidal CdSe nanocrystal films

Philippe Guyot-Sionnest, Dong Yu, Pei Hsun Jiang, Woowon Kang

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

The conduction of thin films of n -type CdSe colloidal quantum dots is studied at low temperature and under magnetic field. At medium and high magnetic fields (10 T), the films exhibit positive magnetoresistance consistent with the variable range hopping model. At low magnetic field (<0.3 T) but in the strong electric field regime, there is a narrower magnetoresistance of order 10%-15%. The magnetoresistance shows a strong bias dependence, small and positive at low bias, increasing but still positive at higher bias, and turning negative at the highest bias. A similar behavior has been reported recently for thin film organics. Weak localization effects are ruled out. The explanation for the observations is based on spin blockade relaxed by the hyperfine interaction. The weak magnetoresistance at low bias is attributed to the diffusing paths taken by the hopping electrons. At higher bias, the more directed motion of electrons leads to increasingly positive magnetoresistance due to the more effective spin blockade. At the highest bias, the magnetoresistance becomes negative, which is attributed to the increased exchange interaction associated with the shorter tunneling distance.

Original languageEnglish
Article number014702
JournalJournal of Chemical Physics
Volume127
Issue number1
DOIs
Publication statusPublished - 2007 Aug 17

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Magnetoresistance
Nanocrystals
nanocrystals
conduction
Magnetic fields
Thin films
magnetic fields
Electrons
Exchange interactions
Semiconductor quantum dots
thin films
Electric fields
electrons
quantum dots
interactions
electric fields

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

Spin blockade in the conduction of colloidal CdSe nanocrystal films. / Guyot-Sionnest, Philippe; Yu, Dong; Jiang, Pei Hsun; Kang, Woowon.

In: Journal of Chemical Physics, Vol. 127, No. 1, 014702, 17.08.2007.

Research output: Contribution to journalArticle

Guyot-Sionnest, Philippe ; Yu, Dong ; Jiang, Pei Hsun ; Kang, Woowon. / Spin blockade in the conduction of colloidal CdSe nanocrystal films. In: Journal of Chemical Physics. 2007 ; Vol. 127, No. 1.
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