Enhancement of room temperature ferromagnetism of Fe-doped ZnO epitaxial thin films with Al co-doping

• Published in: Journal of magnetism and magnetic materials Vol. 323; no. 8; pp. 1033 - 1039
• Main Authors: Chattopadhyay, S., Nath, T.K., Behan, A.J., Neal, J.R., Score, D., Feng, Q., Fox, A.M., Gehring, G.A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-04-2011; Elsevier
• Subjects: Aluminum; Antiferromagnetic coupling; Carrier density; Carrier induced ferromagnetism; Carriers; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Defect state; Dilute magnetic semiconductor; Electrical properties of specific thin films; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Epitaxy; Exact sciences and technology; Ferromagnetism; Ii-vi semiconductors; Iron; Magnetic properties and materials; Magnetic properties of monolayers and thin films; Magnetic properties of surface, thin films and multilayers; Magnetic semiconductors; Magnetization; Order disorder; Physics; Spinodal decomposition; Studies of specific magnetic materials; Thin films; Zinc oxide; Defect state; Antiferromagnetic coupling; Carrier induced ferromagnetism; Spinodal decomposition; Dilute magnetic semiconductor; Epitaxial layers; Magnetization; Doping; Hall effect; Coulomb interaction; Electron-electron interactions; Magnetic thin films; Optimization; Semimagnetic semiconductors; Hopping conduction; Magnetic impurities; Zinc oxide; Ferromagnetism; Iron additions; Donor center; Carrier density; Saturation magnetization
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2010.11.090

Epitaxial films of ZnO doped with magnetic ion Fe and, in some cases, with 1% Al show clear evidence of room temperature ferromagnetic ordering. The Al doped optimized samples with carrier concentration
n
c∼8.0×10
20
cm
−3 show about 3 times enhanced saturation magnetization (0.58
μ
B/Fe
2+) than the one with
n
c∼3.0×10
20
cm
−3 (0.18
μ
B/Fe
2+). A clear correlation between the magnetization per transition metal ion and the ratio of the number of carriers to the number of donors have been found as is expected for carrier-induced room temperature ferromagnetism. The transport mechanism of the electrons in all the DMS films at low temperature range has been identified with the Efros's variable range hopping due to the electron–electron Coulomb interaction.
► Epitaxial films of ZnO doped with magnetic ion Fe and, in some cases, with 1% Al show clear evidence of room temperature ferromagnetic ordering. ► The Al doped optimized samples with carrier concentration
n
c∼8.0×10
20
cm
−3 show about 3 times enhanced saturation magnetization (0.58
μ
B/Fe
2+) than the one with
n
c∼3.0×10
20
cm
−3 (0.18
μ
B/Fe
2+). ► A clear correlation between the magnetization per transition metal ion and the ratio of the number of carriers to the number of donors have been found as is expected for carrier-induced room temperature ferromagnetism. ► The transport mechanism of the electrons in all the DMS films at low temperature range has been identified with the Efros's variable range hopping due to the electron–electron Coulomb interaction.