Ferromagnetism induced by oxygen and cerium vacancies above the percolation limit in CeO2

被引：75

作者：

Fernandes, V. ^{[1
]}

Schio, P. ^{[2
]}

de Oliveira, A. J. A. ^{[2
]}

Ortiz, W. A. ^{[2
]}

Fichtner, P. ^{[3
]}

Amaral, L. ^{[4
]}

Graff, I. L. ^{[5
]}

Varalda, J. ^{[5
]}

Mattoso, N. ^{[5
]}

Schreiner, W. H. ^{[5
]}

Mosca, D. H. ^{[5
]}

机构：

[1] Univ Fed Parana, PIPE, BR-81531990 Curitiba, Parana, Brazil

[2] Univ Fed Sao Carlos, Dept Fis, BR-13565905 Sao Carlos, SP, Brazil

[3] Univ Fed Rio Grande do Sul, Escola Engn, BR-91501970 Porto Alegre, RS, Brazil

[4] Univ Fed Rio Grande do Sul, Inst Fis, BR-91501970 Porto Alegre, RS, Brazil

[5] Univ Fed Parana, Dept Fis, BR-81531990 Curitiba, Parana, Brazil

来源：

JOURNAL OF PHYSICS-CONDENSED MATTER | 2010年 / 22卷 / 21期

基金：

巴西圣保罗研究基金会;

关键词：

X-RAY-ABSORPTION; PHOTOELECTRON-SPECTROSCOPY; INDUCED REDUCTION; CRYSTALLINE; STATE; PURE;

D O I：

10.1088/0953-8984/22/21/216004

中图分类号：

O469 [凝聚态物理学];

学科分类号：

070205 ;

摘要：

We studied the structural, chemical and magnetic properties of non-doped ceria (CeO2) thin films electrodeposited on silicon substrates. Experimental results confirm that the observed room temperature ferromagnetism is driven by both cerium and oxygen vacancies. We investigated ceria films presenting vacancy concentrations well above the percolation limit. Irradiation experiments with neon ions were employed to generate highly oxygen defective CeO2-delta structures. X-ray photoelectron spectroscopy and x-ray absorption near-edge structure spectroscopy were used to estimate the concentration of Ce3+ sites in the films, which can reach up to 50% of Ce3+ replacing Ce4+, compared to a stoichiometric CeO2 structure. Despite the increment of structural disorder, we observe that the saturation magnetization continuously increases with Ce3+ concentration. Our experiments demonstrate that the ferromagnetism observed in ceria thin films, highly disordered and oxygen-deficient, preserving the fluorite-type structure only in a nanometer scale, remains intrinsically stable at room temperature.

引用

页数：8

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