Quantum phase transition from superparamagnetic to quantum superparamagnetic state in ultrasmall Cd 1- xCr(II) xSe quantum dots?

Weiwei Zheng, Pushpendra Kumar, Aaron Washington, Zhenxing Wang, Naresh S. Dalal, Geoffrey F. Strouse, Kedar Singh

Research output: Contribution to journalArticle

41 Scopus citations

Abstract

Despite a long history of success in formation of transition-metal-doped quantum dots (QDs), the origin of magnetism in diluted magnetic semiconductors (DMSs) is yet a controversial issue. Cr(II)-doped II-VI DMSs are half-metallic, resulting in high-temperature ferromagnetism. The magnetic properties reflect a strong p-d exchange interaction between the spin-up Cr(II) t 2g level and the Se 4p. In this study, ultrasmall (∼3.1 nm) Cr(II)-doped CdSe DMSQDs are shown to exhibit room-temperature ferromagnetism, as expected from theoretical arguments. Surprisingly, a low-temperature phase transition is observed at 20 K that is believed to reflect the onset of long-range ordering of the single-domain DMSQD.

Original languageEnglish (US)
Pages (from-to)2172-2179
Number of pages8
JournalJournal of the American Chemical Society
Volume134
Issue number4
DOIs
StatePublished - Feb 1 2012
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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