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

doi:10.1021/ja2088426

Quantum phase transition from superparamagnetic to quantum superparamagnetic state in ultrasmall Cd _{1- x}Cr(II) _xSe quantum dots?

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

Research output: Contribution to journal › Article › peer-review

52 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 language	English (US)
Pages (from-to)	2172-2179
Number of pages	8
Journal	Journal of the American Chemical Society
Volume	134
Issue number	4
DOIs	https://doi.org/10.1021/ja2088426
State	Published - Feb 1 2012
Externally published	Yes

ASJC Scopus subject areas

Catalysis
General Chemistry
Biochemistry
Colloid and Surface Chemistry

Access to Document

10.1021/ja2088426

Cite this

@article{2a49878b41e247c19ff90f8660585e66,

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

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.",

author = "Weiwei Zheng and Pushpendra Kumar and Aaron Washington and Zhenxing Wang and Dalal, {Naresh S.} and Strouse, {Geoffrey F.} and Kedar Singh",

year = "2012",

month = feb,

day = "1",

doi = "10.1021/ja2088426",

language = "English (US)",

volume = "134",

pages = "2172--2179",

journal = "Journal of the American Chemical Society",

issn = "0002-7863",