Low temperature Electrical and Magnetic studies of Nsutite

Nsutite is a naturally occurring Manganese Oxide of the composition Mn$^{4+}_{1-x}$Mn$^{2+}_{x}$O$_{2-2x}$(OH)$_{2x}$ where x = 0.06 -- 0.07. D.C. electrical transport measurements were carried out on samples from Nsuta, Ghana between 40 K and 400 K. Non-linear I-V curves were observed below 140 K even at very low currents. The resistivity vs. temperature data suggests electron transport is by the variable range hopping mechanism between 140 K and 400 K. Magnetic moment vs. temperature data were obtained between 5K and 300K at high field (10,000 Oe) and low field (1,000 Oe). Both high and low field data suggest paramagnetic behavior with a possible Neel temperature at about 15K, below which the materials exhibits antiferromagnetic behavior. The electrical and magnetic properties as well as high temperature thermal analysis (DSC) data will be discussed.