Large low-field magnetoresistance of a two-layered La 2-2 xCa 1+2 xMn 2O 7 polycrystal
Abstract
Magnetotransport properties of a two-layered La 2-2 xCa 1+2 xMn 2O 7 ( x=0.2) polycrystal have been studied as function of temperatures and applied fields. It was found that the variation of the resistivity with temperature at high temperatures obeys the variable-range hopping law under various applied fields. Two maxima of magnetoresistance (MR) were observed under applied fields of 1 and 0.15 T, while no MR peaks were found under applied field of 0.1 T. At 10 K, the MR attain as large as -17%, -25% and -30% under applied fields of 0.05, 0.1 and 0.15 T, respectively. The large low-field MR at low temperatures can be attributed to the effects of the nearly fully spin-polarized carriers' tunneling through the insulating (La,Ca) 2O 2 layers between the adjacent MnO 2 bilayers.
- Publication:
-
Physics Letters A
- Pub Date:
- April 2001
- DOI:
- 10.1016/S0375-9601(01)00182-7
- Bibcode:
- 2001PhLA..282..209Z