TEM image of a single-crystal Bi film, showing individual atoms.	Magnetoresistance of a single-crystal Bi film.

We have developed a new fabrication method using electrodeposition that achieves high-quality single-crystal Bi thin films. These films exhibit very large magnetoresistance (MR) effects of as much as 380,000% at low temperatures and 250% at room temperature, with a non-hysteretic and quasi-linear field dependence. The high quality of the Bi films is further illustrated by the observation of clean Shubnikov-de Haas (S-dH) oscillations. Field sensing characteristics have been demonstrated in a simple hybrid structure, which shows a large MR effect of 30% at 200 Oe and a field sensitivity of 0.2 %/Oe at room temperature. These electrodeposited Bi thin films are new media suitable for studying the unusual transport properties of Bi and the development of field-sensing devices.

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PUBLICATIONS:

• F. Y. Yang, Kai Liu, Kimin Hong, D. H. Reich, P. C. Searson, and C. L. Chien, "Large Magnetoresistance of Electrodeposited Single-Crystal Bismuth Thin Films," Science 284, 1335 (1999). (pdf)
• F. Y. Yang, Kai Liu, C. L. Chien, and P. C. Searson, "Large Magnetoresistance and Finite-Size Effects in Electrodeposited Single-Crystal Bi Thin Films," Phys. Rev. Lett. 82, 3328 (1999).
• F. Y. Yang, Kai Liu, Kimin Hong, D. H. Reich, P. C. Searson, C. L. Chien, Y. Leprince-Wang, Kui Yu-Zhang, and Ke Han, "Shubnilov-de Haas Oscillations in Electrodeposited Single-Crystal Bismuth Films," Phys. Rev. B 61, 6631 (2000).