Effect of cation size and size-disorder on the magnetic and electron transport properties of La_(0.7-x)Ln_xSr_(0.3)MnO_3 (Ln = Gd and Dy)

摘要

Magnetic and electron transport properties of La_(0.7-x)Ln_xSr_(0.3)MnO_3 with Ln = Gd and Dy have been investigated over a wide range of compositions to explore the effects of the radius of the A-site cation, , and the size-disorder as measured by a . These manganates exhibit ferromagnetism and insulator-metal transitions up to a critical value of x (x_c), with the T_c (T_(IM)) values decreasing with . When x >= x_c, however, the manganates cease to be ferromagnetic and instead they show an abrupt decrease in magnetization and increase in resistivity, suggesting the likely occurrence of electronic phase separation.