Paramagnetic properties of Cuban red mud at low temperatures

Abstract

The electron spin resonance (ESR) spectra of Cuban red mud have been measured at three different temperatures: 295 K, 150 K and 77 K. The broad absorption line with resonance fields ∼(1.7–1.8) kOe was observed at all temperatures with values of $\overline{g}$-factor from 3.602 to 4.020. The temperature decrease resulted in an absorption line appearance with resonance fields of 3.252 kOe ($\overline{g}$=2.067) at 150 K and 3.339 kOe ($\overline{g}$=2.086) at 77 K. The ESR-signal amplitude with resonance fields ∼(1.7–1.8) kOe decreases and the ESR-signal amplitude in the field ∼3.3 kOе increases with reduction in temperature.