Observation of enhanced positive magnetoresistance at low temperatures in Ni0.8Fe0.2/C granular composites

Role of particle size on the magnetoresistance of nano-crystalline graphite

“…Also no good fits could be obtained for the variable range hopping (VRH) expressions. However a semi-classical model, which is based on fluctuation induced tunneling (FIT) has been applied earlier to explain the conduction process in graphite [21], permalloy-graphite [3,4] and RuO 2 nanowire [22]. This mechanism is based on thermal fluctuations of electric potential on the edges of a tunneling gap.…”

“…The spin dependent transport observed in giant magnetoresistance (GMR) materials normally generates large negative magnetoresistance (MR) values. In contrast, large anomalous positive MR was reported in non-magnetic silver chalcogenides [1], inhomogeneous narrow-gap semiconductors [2], permalloygraphite composites [3,4] and semimetals [5,6]. Graphite is also a semimetallic layered element with low carrier concentration (n) of electrons and holes.…”