Europhys. Lett.
Volume 74, Number 3, May 2006
Page(s) 526 - 532
Section Interdisciplinary physics and related areas of science and technology
Published online 29 March 2006
Europhys. Lett., 74 (3), pp. 526-532 (2006)
DOI: 10.1209/epl/i2006-10011-3

The evolution of magnetotransport properties with carrier concentration in $\chem{Ca_{3}Co_{4}O_{9+\delta}}$ single crystals

X. G. Luo, X. H. Chen, G. Y. Wang, C. H. Wang, Y. M. Xiong, H. B. Song and X. X. Lu

Hefei National Laboratory for Physical Science at Microscale and Department of Physics University of Science and Technology of China - Hefei, Anhui 230026, PRC

received 15 January 2006; accepted in final form 2 March 2006
published online 29 March 2006

Magnetotransport properties are systematically investigated on $\chem{Ca_{3}Co_{4}O_{9+\delta}}$ single crystals with different carrier concentrations changed by oxygen content. The in-plane resistivity decreases rapidly with increasing carrier concentration. Large negative magnetoresistance was observed in all the single crystals. A magnetic-field-driven sign change of the slope in resistivity at $25\un{K}$ and a magnetic-dependent energy gap in the range 20-$60\un{K}$ are observed in highly doped crystals, while they are absent in the crystals with low carrier concentrations. In addition, a thermally activated resistivity induced by magnetic fields was observed at low temperatures below $12\un{K}$ in highly doped crystals. It is concluded that the magnetotransport properties are quite sensitive to the carrier concentration.

81.40.Rs - Electrical properties (related to treatment conditions).
75.47.-m - Magnetotransport phenomena; materials for magnetotransport.
72.15.Gd - Galvanomagnetic and other magnetotransport effects.

© EDP Sciences 2006