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Magnetic Rare Earth (Gd) Implanted Tetrahedral Amorphous Carbon (ta-C)

Published online by Cambridge University Press:  01 February 2011

Li Zeng
Affiliation:
li_zeng@berkeley.edu, University of California, San Diego, Materials Science and Engineering Program, 2306 Roosevelt Ave., Berkeley, CA, 94703, United States, 510-643-4112, 510-643-8497
Erik Helgren
Affiliation:
helgren@berkeley.edu, University of California, Berkeley, Physics Department, 366 Le Conte, Berkeley, CA, 94720, United States
Hayo Zutz
Affiliation:
hzutz@gwdg.de, University of Göttingen, II. Institute of Physics, Friedrich-Hund-PLatz 1, Gottingen, N/A, 37077, Germany
Carsten Ronning
Affiliation:
Carsten.Ronning@phys.uni-goettingen.de, University of Göttingen, II. Institute of Physics, Friedrich-Hund-PLatz 1, Gottingen, N/A, 37077, Germany
Frances Hellman
Affiliation:
fhellman@berkeley.edu, University of California, Berkeley, Physics Department, 366 Le Conte, Berkeley, CA, 94720, United States
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Abstract

Tetrahedrally bonded amorphous carbon (ta-C) thin films were prepared by mass selected ion beam deposition (MSIBD) using 100 eV carbon ions at room temperature. Gadolinium, a magnetic rare earth element, was implanted as a dopant into ta-C with two different fluences. The doping level of the ta-C:Gdx layers was in maximum 4 or 7 at.%, respectively. The Gd is believed to be electrically activated in as-implanted films, although contributions from the sp2 sites cannot be ruled out. A transition temperature (T') was found, below which there is a large negative magnetoresistance (MR) with a strong temperature dependence. Thermal annealing greatly increases the sample conductivity due to the increase of sp2 sites. However, the MR persists at least up to an annealing temperature of 500°C. Magnetically, the Gd dopants behave like non-interacting local moments. Similarities and differences in physical properties between the ta-C:Gdx films and other Gd doped amorphous semiconductors are compared.

Type
Research Article
Copyright
Copyright © Materials Research Society 2006

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References

1 Hellman, F., Tran, M. Q., Gebala, A. E., Wilcox, E. M., Dynes, R. C., Phys. Rev. Lett. 77 4652 (1996).Google Scholar
2 Xiong, P., Zink, B. L., Applebaum, S. I., Hellman, F., Dynes, R. C., Phys. Rev. B 59, R3929 (1999).Google Scholar
3 Helgren, E., Cherry, J., Zeng, L., Hellman, F., Phys. Rev. B 71 113203 (2005).Google Scholar
4 Robertson, J., Mater. Sci. Eng., R 37 129 (2002).Google Scholar
5 Ronning, C., Appl. Phys. A 77, 39 (2003)Google Scholar
6 Ziegler, J.F., Biersack, J.P., and Littmark, U., The Stopping and Ranges of Ions in Solids, (Pergamon Press, New York, 1985). See also www.srim.org.Google Scholar
7 Ferrari, A.C., Robertson, J., Phys. Rev. B 61 14095 (2000).Google Scholar
8 Kröger, H., Ronning, C., Hofsäss, H., Neumaier, P., Bergmaier, A., Görgens, L., Dollinger, G., Diamond Relat. Mater. 12 2042 (2003).Google Scholar
9 Hellman, F., Queen, D. R., Potok, R. M., Zink, B. L., Phys. Rev. Lett. 84, 5411 (2000)Google Scholar
10 Guillotel, E., Zeng, L., Helgren, E., Hellman, F., Islam, R., Smith, D., to be published.Google Scholar