Defect-band mediated ferromagnetism in Gd-doped ZnO thin films

Venkatesh, S.; Franklin, J. B.; Ryan, M. P.; Lee, J.-S.; Ohldag, Hendrik; McLachlan, M. A.; Alford, N. M.; Roqan, Iman S.

Defect-band mediated ferromagnetism in Gd-doped ZnO thin films

Files

1.4905585.pdf (1.71 MB)

Type

Article

Authors

Venkatesh, S.
Franklin, J. B.
Ryan, M. P.
Lee, J.-S.
Ohldag, Hendrik
McLachlan, M. A.
Alford, N. M.
Roqan, Iman S.

KAUST Department

Material Science and Engineering Program
Physical Science and Engineering (PSE) Division
Semiconductor and Material Spectroscopy (SMS) Laboratory

Online Publication Date

2015-01-07

Print Publication Date

2015-01-07

Date

2015-01-07

Abstract

Gd-doped ZnO thin films prepared by pulsed laser deposition with Gd concentrations varying from 0.02–0.45 atomic percent (at. %) showed deposition oxygen pressure controlled ferromagnetism. Thin films prepared with Gd dopant levels (<Gd 0.112 at. %) at low oxygen deposition pressure (<25 mTorr) were ferromagnetic at room temperature. Negative magnetoresistance, electric transport properties showed that the ferromagnetic exchange is mediated by a spin-split defect band formed due to oxygen deficiency related defect complexes. Mott's theory of variable range of hopping conduction confirms the formation of the impurity/defect band near the Fermi level.

Citation

Defect-band mediated ferromagnetism in Gd-doped ZnO thin films 2015, 117 (1):013913 Journal of Applied Physics

Acknowledgements

The authors acknowledge the financial support from the Academic Excellence Alliance (AEA) Grant from King Abdullah University of Science and Technology (KAUST), Saudi Arabia. We thank Dr. Katharina, Lorenz Instituto Superior Técnico, Universidade de Lisboa, Portugal for fitting the RBS data. Soft X-ray spectroscopic studies were carried out at the SSRL, a Directorate of SLAC and an Office of Science User Facility operated for the U.S. DOE Office of Science by Stanford University. J.S.L. acknowledges partial support by the Department of Energy, Office of Basic Energy Sciences, Materials Sciences and Engineering Division, under Contract No. DE-AC02-76SF00515.