Anomalous magnetism and charge transport in dielectric La1−xCaxMnO3 (x≤xMIT∼0.22)

A study of the charge transport, magnetization, and high frequency (ω/2π=60 GHz) electron spin resonance (ESR) has been carried out on La1−xCaxMnO3 single crystals corresponding to the dielectric side of the concentration driven metal-insulator transition (x≤xMIT∼0.22). For x=0.22 the onset of ferromagnetism below the Curie temperature TC≈183 K was found to induce crossover from holelike (T>TC) to electronlike (TTC. A large enhancement of the Hall effect, which is accompanied by the increase in Hall mobility to the values of μH∼−20 cm2/V s, was observed at intermediate temperatures 150 K