Colossal Magnetoresistance Without Double Exchange Mechanism in Spinel FeCr2S4
SHI Lei, DONG Qiu-zhao, YANG Zhao-rong, CHEN Zhi-wen, ZHANG Yu-heng
Structure Research Laboratory, University of Science and Technology of China, Hefei 230026
and Center for Advanced Studies in Science and Technology of Microstructures, Nanjing University, Nanjing 210093
Colossal Magnetoresistance Without Double Exchange Mechanism in Spinel FeCr2S4
SHI Lei;DONG Qiu-zhao;YANG Zhao-rong;CHEN Zhi-wen;ZHANG Yu-heng
Structure Research Laboratory, University of Science and Technology of China, Hefei 230026
and Center for Advanced Studies in Science and Technology of Microstructures, Nanjing University, Nanjing 210093
Abstract： The crystal structure of spinel FeCr2S4, which shows a semiconductor-metal transition and paramagnetic-ferrimagnetic transition at Tc = 170K , was determined by x-ray powder diffraction. It is found that the spinel FeCr2S4 belongs to a normal spinel structure [Fe2+]t[Cr3+2]oS4. The result clearly shows that the spinel FeCr2S4 has neither mixed valence of Fe3+ and Fe2+ ions or Cr3+ and Cr2+ ions for a double-exchange magnetic interaction, nor a Jahn-Teller cation such as Cr3+. The spinels represent a distinct class of colossal magnetoresistance materials, with magnetic ordering driven by superexchange rather than double exchange.
1999, Vol. 16 
