The level-shifting–induced negative magnetoresistance in the nearest-neighbor hopping conduction
Department of Physics, The Hong Kong University of Science
and Technology Clear Water Bay, Hong Kong
2 Department of Physics, Oklahoma State University - Stillwater, OK 74078, USA
Accepted: 26 November 1998
We propose a new mechanism of negative magnetoresistance in non-magnetic granular materials in which electron transport is dominated by hopping between two nearest-neighbor clusters. We study the dependence of magnetoresistance on temperature and separation between neighboring clusters. At a small separation we find a negative magnetoresistance at low temperatures and it changes over to a positive value as temperature increases. For a fixed temperature, magnetoresistance changes from negative to positive when the cluster separation increases. The change of magnetoresistance can be more than 80 % at low temperatures.
PACS: 72.80.Tm – Composite materials / 75.70.Pa – Giant magnetoresistance / 81.05.Rm – Porous materials; granular materials
© EDP Sciences, 1999