Strong room-temperature ferromagnetism in Co2+-doped TiO2 made from colloidal nanocrystals

被引：219

作者：

Bryan, JD

Heald, SM

Chambers, SA

Gamelin, DR ^{[1
]}

机构：

[1] Univ Washington, Dept Chem, Seattle, WA 98195 USA

[2] Pacific NW Natl Lab, Fundamental Sci Directorate, Richland, WA 99352 USA

来源：

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY | 2004年 / 126卷 / 37期

关键词：

D O I：

10.1021/ja047381r

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

Colloidal cobalt-doped TiO2 (anatase) nanocrystals were synthesized and studied by electronic absorption, magnetic circular dichroism, transmission electron microscopy, magnetic susceptibility, cobalt K-shell X-ray absorption spectroscopy, and extended X-ray absorption fine structure measurements. The nanocrystals were paramagnetic when isolated by surface-passivating ligands, weakly ferromagnetic (M-s approximate to 1.5 x 10(-3) mu(B)/Co2+ at 300 K) when aggregated, and strongly ferromagnetic (up to M-s = 1.9 mu(B)/Co2+ at 300 K) when spin-coated into nanocrystalline films. X-ray absorption data reveal that cobalt is in the Co2+ oxidation state in all samples. In addition to providing strong experimental support for the existence of intrinsic ferromagnetism in cobalt-doped TiO2, these results demonstrate the possibility of using colloidal TiO2 diluted magnetic semiconductor nanocrystals as building blocks for assembly of ferromagnetic semiconductor nanostructures with potential spintronics applications.

引用

页码：11640 / 11647

页数：8

共 55 条

[41] Electronic absorption spectroscopy of cobalt ions in diluted magnetic semiconductor quantum dots: Demonstration of an isocrystalline core/shell synthetic method
Radovanovic, PV
Gamelin, DR
[J]. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2001, 123 (49) : 12207 - 12214
[42] Very large magnetoresistance in lateral ferromagnetic (Ga,Mn)As wires with nanoconstrictions -: art. no. 216602
Rüster, C
Borzenko, T
Gould, C
Schmidt, G
Molenkamp, LW
Liu, X
Wojtowicz, TJ
Furdyna, JK
Yu, ZG
Flatté, ME
[J]. PHYSICAL REVIEW LETTERS, 2003, 91 (21)
[43] Special issue on "sol-gel processed TiO2-based materials for solar cells, photocatalysts and other applications" -: Editor's preface
Sakka, S
[J]. JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY, 2001, 22 (1-2) : 5 - 5
[44] Magnetic quantum dots:: Synthesis, spectroscopy, and magnetism of CO2+- and Ni2+-doped ZnO nanocrystals
Schwartz, DA
Norberg, NS
Nguyen, QP
Parker, JM
Gamelin, DR
[J]. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2003, 125 (43) : 13205 - 13218
[45] SCHWARTZ DA, 2004, CONDMAT0404518, P1
[46] Ferromagnetism in laser deposited anatase Ti1-xCoxO2-δ films -: art. no. 115211
Shinde, SR
Ogale, SB
Das Sarma, S
Simpson, JR
Drew, HD
Lofland, SE
Lanci, C
Buban, JP
Browning, ND
Kulkarni, VN
Higgins, J
Sharma, RP
Greene, RL
Venkatesan, T
[J]. PHYSICAL REVIEW B, 2003, 67 (11) : 6
[47] Co-occurrence of superparamagnetism and anomalous Hall effect in highly reduced cobalt-doped rutile TiO2-δ films -: art. no. 166601
Shinde, SR
Ogale, SB
Higgins, JS
Zheng, H
Millis, AJ
Kulkarni, VN
Ramesh, R
Greene, RL
Venkatesan, T
[J]. PHYSICAL REVIEW LETTERS, 2004, 92 (16) : 166601 - 1
[48] Local environment surrounding magnetic impurity atoms in a structural phase transition of Co-doped TiO2 nanocrystal ferromagnetic semiconductors
Soo, YL
Kioseoglou, G
Kim, S
Kao, YH
Devi, PS
Parise, J
Gambino, RJ
Gouma, PI
[J]. APPLIED PHYSICS LETTERS, 2002, 81 (04) : 655 - 657
[49] Synthesis and characterization of dilute magnetic semiconductor manganese-doped indium arsenide nanocrystals
Stowell, CA
Wiacek, RJ
Saunders, AE
Korgel, BA
[J]. NANO LETTERS, 2003, 3 (10) : 1441 - 1447
[50] Theory of dopants and defects in Co-doped TiO2 anatase -: art. no. 144415
Sullivan, JM
Erwin, SC
[J]. PHYSICAL REVIEW B, 2003, 67 (14)

← 1 2 3 4 5 6 →