Showing papers by "Joshua E. Goldberger published in 2000"

Phase separation over an extended compositional range: Studies of the Ca 1-x Bi x MnO 3 (x<=0.25) phase diagram

Abstract: Phase transitions on the electron-doped side of the Ca{sub 1-x}Bi{sub x}MnO{sub 3} system (x{ =}x{ge}0.03, is characterized by the absence of charge and orbital ordering, a canted G-type antiferromagnetic spin structure, and delocalized electron transport. The second phase, observed from 0.25{>=}x{ge}0.12 (single phase at x=0.18), is characterized by pronounced orbital ordering, a C-type antiferromagnetic spin structure, and insulating behavior. The third low-temperature phase, observed for x{>=}0.20, is characterized by orbital and magnetic ordering similar to the Wigner crystal structure previously observed for Ca{sub 0.67}La{sub 0.33}MnO{sub 3}, but with a 4axbx2c unit cell. The most striking feature of the phase diagram is the wide compositional range over which low-temperature phase separation is observed. Only those samples with x<0.12 and x=0.18 did not undergo phase separation upon cooling. We show that thismore » behavior cannot be attributed to compositional variations, and therefore, propose that anisotropic strain interactions between crystallites may be partially responsible for this behavior.« less