1. Metal-semiconductor-transition observed in Bi2Ca(Sr, Ba)2Co2O8+δ single crystals
- Author
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Jian Zhou, Lunyong Zhang, Yu-Lei Chen, Binbin Zhang, Song-Tao Dong, Shu-Hua Yao, Yan-Feng Chen, Shan-Tao Zhang, and Zheng-Bin Gu
- Subjects
Anderson localization ,Valence (chemistry) ,Physics and Astronomy (miscellaneous) ,Magnetoresistance ,Condensed matter physics ,Photoemission spectroscopy ,Chemistry ,Fermi level ,Analytical chemistry ,Electronic structure ,Metal ,symbols.namesake ,visual_art ,visual_art.visual_art_medium ,Density of states ,symbols - Abstract
Electrical property evolution of Bi2AE2Co2O8+δ single crystals (AE = Ca, Sr and Ba) is systematically explored. When AE changes from Ca to Ba, the electrical property of Bi2Ca2Co2O8+δ and Bi2Sr2Co2O8+δ demonstrates semiconductor-like properties. But Bi2Ba2Co2O8+δ shows the metallic behavior. Analysis of temperature-dependent resistance substantiates that from metallic Bi2Ba2Co2O8+δ to semiconductor-like Bi2Sr2Co2O8+δ can be attributed to Anderson localization. However the semiconductor behaviour of Bi2Sr2Co2O8+δ and Bi2Ca2Co2O8+δ is related to electronic correlations effect that is inferred by large negative magnetoresistance (∼70%). The theoretical electronic structures and valence X-ray photoemission spectroscopy substantiate that there is a relative large density of state around Fermi level in Bi2Ba2Co2O8+δ compared with other two compounds. It suggests that Bi2Ba2Co2O8+δ is more apt to be metal in this material system.
- Published
- 2014