Intrinsic and spatially nonuniform ferromagnetism in Co-doped ZnO films

被引：26

作者：

Tseng, L. T. ^{[1
]}

Suter, A. ^{[2
]}

Wang, Y. R. ^{[1
]}

Xiang, F. X. ^{[3
]}

Bian, P. ^{[4
]}

Ding, X. ^{[1
]}

Tseng, A. ^{[1
]}

Hu, H. L. ^{[1
]}

Fan, H. M. ^{[5
]}

Zheng, R. K. ^{[4
]}

Wang, X. L. ^{[3
]}

Salman, Z. ^{[2
]}

Prokscha, T. ^{[2
]}

Suzuki, K. ^{[6
]}

Liu, R. ^{[7
]}

Li, S. ^{[1
]}

Morenzoni, E. ^{[2
]}

Yi, J. B. ^{[1
]}

机构：

[1] UNSW, Sch Mat Sci & Engn, Sydney, NSW 2052, Australia

[2] Paul Scherrer Inst, Lab Muon Spin Spect, CH-5232 Villigen, Switzerland

[3] Univ Wollongong, Inst Superconducting & Elect Mat, Wollongong, NSW 2522, Australia

[4] Univ Sydney, Sch Phys, Sydney, NSW 2006, Australia

[5] Northwest Univ, Coll Chem & Mat Sci, Xian 710069, Shaanxi, Peoples R China

[6] Monash Univ, Dept Mat Sci & Engn, Clayton, Vic 3800, Australia

[7] Western Sydney Univ, SIMS Facil, Off Deputy Vice Chancellor Res & Dev, Locked Bag 1797, Penrith, NSW 2751, Australia

来源：

PHYSICAL REVIEW B | 2017年 / 96卷 / 10期

基金：

澳大利亚研究理事会;

关键词：

ROOM-TEMPERATURE FERROMAGNETISM; MAGNETIC SEMICONDUCTORS; THIN-FILMS; ORIGIN; GAP;

D O I：

10.1103/PhysRevB.96.104423

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

Co doped ZnO films have been deposited by a laser- molecular beam epitaxy system. X-ray diffraction and UV spectra analysis show that Co effectively substitutes the Zn site. Transmission electron microscopy (TEM) and secondary ion mass spectroscopy analysis indicate that there are no clusters. Co dopants are uniformly distributed in ZnO film. Ferromagnetic ordering is observed in all samples deposited under an oxygen partial pressure, PO2 = 10(-3), 10(-5), and 10(-7) torr, respectively. However, the magnetization of PO2 = 10(-3) and 10(-5) is very small at room temperature. At low temperature, the ferromagnetic ordering is enhanced. Muon spin relaxation (mu SR) measurements confirm the ferromagnetism in all samples, and the results are consistent with magnetization measurements. From mu SR and TEM analysis, the film deposited under PO2 = 10(-7) torr shows intrinsic ferromagnetism. However, the volume fraction of the ferromagnetism phase is approximately 70%, suggesting that the ferromagnetism is not carrier mediated. Resistivity versus temperature measurements indicate Efros variable range hopping dominates the conductivity. From the above results, we can confirm that a bound magnetic polaron is the origin of the ferromagnetism.

引用

页数：10

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