Temperature and field dependent electronic structure and magnetic properties of LaCoO3 and GdCoO3

The transformation of the band structure of LaCoO3 in the applied magnetic field has been theoretically studied. If the field is below its critical value BC≈65 T, the dielectric band gap decreases with the field, thus giving rise to negative magnetoresistance that is highest at T≈300÷500 K. The critical field is related to the crossover between the low- and high-spin terms of Co3+ ions. The spin crossover results in an insulator–metal transition induced by an increase in the magnetic field. Similar calculations have been done for GdCoO3 which is characterized by large spin gap∼2000 K.