(07E128) Magnetic and charge ordering properties of Bi_(0.6-x)(RE)_xCa_(0.4)MnO_3 (0.0 ≤ x ≤ 0.6) perovskite manganites

摘要

In this work, we studied structural, magnetic, and charge ordering properties of polycrystalline Bi_(0.6-x)(RE)_xCa_(0.4)MnO_3 (x = 0.0, 0.1, 0.2, 0.3, 0.4,0.5, and 0.6) samples, synthesized via solid state reaction route and by taking RE = La, Pr, and Nd, separately. The temperature dependence magnetization measurement reveals that the x = 0.0 compound (BCMO) exhibits a charge ordered (CO) and antiferromagnetic (AFM) phase with the charge ordering temperature (T_(CO)) ~289 K and the antiferromagnetic ordering temperature (T_N) ~136 K. Only a small fraction of La-dopant in BCMO is sufficient to destroy the CO completely, whereas a large concentration of La (viz., x = 0.2 to x = 0.6) promotes ultimately a paramagnetic to ferromagnetic (PM-FM) transition, and the PM-FM transition temperature (T_c) decreases progressively from 241K to 203 K as x increases from 0.2 to 0.5. In contrast, systematic substitution of Pr or Nd at Bi site induces an intriguing interplay between the charge ordering and antiferromagnetism. Our results demonstrate that the value of T_(CO) decreases with increasing value of "x" and the value of T_N increases sharply at both the extremes; however, it remains nearly constant from x = 0.2 to 0.4. In our samples, a glassy magnetic states are also observed at far below the T_N.