Hostname: page-component-586b7cd67f-vdxz6 Total loading time: 0 Render date: 2024-11-23T15:26:47.103Z Has data issue: false hasContentIssue false

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

Published online by Cambridge University Press:  01 February 2011

Li Zeng
Affiliation:
[email protected], 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:
[email protected], University of California, Berkeley, Physics Department, 366 Le Conte, Berkeley, CA, 94720, United States
Hayo Zutz
Affiliation:
[email protected], University of Göttingen, II. Institute of Physics, Friedrich-Hund-PLatz 1, Gottingen, N/A, 37077, Germany
Carsten Ronning
Affiliation:
[email protected], University of Göttingen, II. Institute of Physics, Friedrich-Hund-PLatz 1, Gottingen, N/A, 37077, Germany
Frances Hellman
Affiliation:
[email protected], University of California, Berkeley, Physics Department, 366 Le Conte, Berkeley, CA, 94720, United States
Get access

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

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

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