Magnetoresistance in the paramagnetic insulating state of Pr 0.50Ca0.50CoO3

Abstract

We have studied the magnetic and magnetotransport properties of Pr 0.50Ca0.50CoO3 (prepared using high pressure routes). We find that below the metal-insulator and spin state transition (MIT), the system can be described as a paramagnetic insulator. In this regime, it presents a considerable negative magnetoresistance (20%-40%), while above MIT the magnetoresistance is negligible or even slightly positive. These results seem in contradiction with the spin state picture usually drawn for this system. © 2010 IOP Publishing Ltd.