Magnetic and transport properties of Eu1-xSrxCoO3.

We have studied the magnetic and electronic properties of Eu1-xSrxCoO3 with 0/16≤x≤12/16. In the Sr doping range from 2/16 to 11/16, the ferromagnetic clusters coexist spatially with an antiferromagnetic matrix. The magnetization at low temperatures strongly depends on the Sr concentration x, exhibiting a maximum near half doping, which is described in term of the double-exchange mechanism. The semiconductor-metal transition at low temperatures occurs at x between 4/16 and 5/16, which indicates that the ferromagnetic clusters coalesce, leading to a percolative metallic conduction up to the composition of x=10/16. As compared with those of La1-xSrxCoO3 and Nd1-xSrxCoO3, Eu1-xSrxCoO3 shows a larger critical Sr concentration for semiconductor-metal transition and lower ferromagnetic transition temperatures, which is attributed to the enhanced global and local lattice distortion due to the smaller cation radius of the Eu3+ ions. [ABSTRACT FROM AUTHOR]