Magnetic phase diagram of the manganites Bi1-xSrxMnO3

An experimental study of the crystal structure and the magnetic and elastic properties of the manganites Bi1-xSrxMnO3 is carried out. The following phase transformations are found: ferromagnet (x<0.15)-spin glass (0.15less than or equal toxless than or equal to0.25)-charge-ordered antiferromagnet (0.35less than or equal toxless than or equal to0.8). The ferromagnetic state corresponds to ordering of the orbitals of the Mn3+ ions. It is assumed that the orbitally disordered phase is not realized in the Bi1-xSrxMnO3 system in the concentration interval 0.15less than or equal toxless than or equal to0.35. Samples with 0.25less than or equal toxless than or equal to0.8 undergo a first-order transition of the crystal structure, attributed to ordering of the Mn3+ and Mn4+ ions in the ratios 1:1 (xless than or equal to0.6) and 1:3 (xgreater than or equal to0.7). The antiferromagnetic charge-ordered and spin glass phases coexist in samples with 0.25<x<0.35, possibly because of the martensitic character of the charge order-disorder phase transformation. A hypothetical magnetic phase diagram is constructed. (C) 2004 American Institute of Physics.