Electronic and magnetic phase diagram of SmNi1-xCoxO3

Magnetic and electrical transport properties of SmNi1-xCoxO3 perovskites, with 0 less than or equal to x less than or equal to 1, have been studied in the temperature range 5 less than or equal to T less than or equal to 700 K. This series shows paramagnetic metal. paramagnetic insulator, antiferromagnetic insulator, and spin-glass-like insulator regions. Ferromagnetic interactions between different 3d ions show up at intermediate x concentrations, 0.3 less than or equal to x less than or equal to 0.8, We found a large negative magnetoresistance in the same region. A dynamic mechanism with spin memory, a type of double exchange interaction, can give rise to the observed magnetoresistance and spin-glass behavior. The role played by both electron-electron interactions and structural disorder in electrical transport properties of these systems is discussed. [S0163-1829(99)10321-7].