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Synthesis and characterization of high quality ferromagnetic Cr-doped GaN and AlN thin films with Curie temperatures above 900K

Published online by Cambridge University Press:  01 February 2011

Stephen Y. Wu ,
H. X. Liu ,
Lin Gu ,
R. K. Singh ,
M. van Schilfgaarde ,
David J. Smith ,
N. R. Dilley ,
L. Montes ,
M. B. Simmonds  and
N. Newman
Stephen Y. Wu
Affiliation:
Dept. of Chemical and Materials Engineering, Arizona State University, Tempe, AZ 85287–6006
H. X. Liu
Affiliation:
Dept. of Chemical and Materials Engineering, Arizona State University, Tempe, AZ 85287–6006
Lin Gu
Affiliation:
Center for Solid State Science, Arizona State University, Tempe, AZ 85287
R. K. Singh
Affiliation:
Dept. of Chemical and Materials Engineering, Arizona State University, Tempe, AZ 85287–6006
M. van Schilfgaarde
Affiliation:
Dept. of Chemical and Materials Engineering, Arizona State University, Tempe, AZ 85287–6006
David J. Smith
Affiliation:
Center for Solid State Science, Arizona State University, Tempe, AZ 85287 Dept. of Physics and Astronomy, Arizona State University, Tempe, AZ 85287–1504
N. R. Dilley
Affiliation:
Quantum Design, San Diego, CA 92121
L. Montes
Affiliation:
Quantum Design, San Diego, CA 92121
M. B. Simmonds
Affiliation:
Quantum Design, San Diego, CA 92121
N. Newman
Affiliation:
Dept. of Chemical and Materials Engineering, Arizona State University, Tempe, AZ 85287–6006
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Abstract

Reactive MBE growth was used to synthesize ferromagnetic Cr-doped GaN and AlN thin films with Curie temperatures above 900K. 2% Cr-doped GaN and 7% Cr-doped AlN were found to have a saturation magnetization moment of 0.42 and 0.6 μB/Cr atom, indicating that ∼14% and ∼20% of the Cr, respectively, are magnetically active. Structural characterization using X-ray diffraction (XRD) and transmission electron microscopy (TEM) did not find evidence of a ferromagnetic secondary phase. Electrical characterization indicate that the resistivity of the Cr-doped GaN films depends exponentially on temperature as R=Roexp[(To/T)1/2], characteristic of variable range hopping. In contrast, Cr-doped AlN films are highly resistive. Local spin density functional calculations predict that Cr forms a deep level defect in both systems and the t2 level falls approximately at midgap. Our theoretical and experimental results indicate that ferromagnetism in Cr-doped GaN and AlN arises as a result of the double exchange mechanism within the partially filled Cr t2 band.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 798: Symposium Y – GaN and Related Alloys , 2003 , Y10.57
Copyright
Copyright © Materials Research Society 2004

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References

REFERENCES

]1] Wolf, S.A., Awschalom, D.D., Buhrman, R.A., Daughton, J.M., Von Molmar, S., Roukes, M.L., Chtchelkanova, A.Y., and Treger, D.M., Science 294, 1488 (2002).Google Scholar
[2] Ohno, H., Shen, A., Matsukura, F., Appl. Phys. Lett. 69, 363 (1996).Google Scholar
[3] Awschalom, D.D., Flatte, M.E., and Samarth, N., Sci. Am. 286, 52 (2002).Google Scholar
[4] Yu, K. M., Walukiewicz, W., Wojtowicz, T., Kuryliszyn, I., Liu, X., Sasaki, Y., and Furdyna, J. K., Phys. Rev. B 65, 201303 (2002).Google Scholar
[5] van Schilfgaarde, M. (unpublished).Google Scholar
[6] Reed, M.L., El Masry, N.A., Stadelmaier, H.H., Ritums, M.K., Reed, M.J., Parker, C.A., Roberts, J.C., Bedair, S.M., Appl. Phys. Lett. 79, 3473 (2001).Google Scholar
[7] Fan, Z. Y. and Newman, N., J. Vac. Sci. Technol. A 16, 2132 (1998).Google Scholar
[8] Fan, Z. Y., Rong, G., and Newman, N., Appl. Phys. Lett. 76 1839 (2000).Google Scholar
[9] Corliss, L.M., Elliott, N., and Hastings, J.M., Phys. Rev. 117, 929 (1960).Google Scholar
[10] van Schilfgaards, M. and Mryasov, O.N., Phy. Rev. B 63 233205 (2001).Google Scholar
[11] Wu, Stephen Y., Liu, H.X., Gu, L., Singh, R.K., Budd, L., van Schilfgaarde, M., McCartney, M.R., Smith, David J., and Newman, N., Appl. Phys. Lett. 82, 3047 (2003).Google Scholar
[12] Liu, H.X., Wu, Stephen Y., Gu, L., Singh, R.K., van Schilfgaarde, M., Smith, David J., Dilley, N.R., Montes, L., Simmonds, M.B., and Newman, N., (unpublished).Google Scholar
[13] American Society of Metals Binary Phase DiagramsGoogle Scholar