2002/05/20 by M. Pissas, G. Kallias · 1 citation
Materials Science · Physics and Astronomy · #Magnetic and transport properties of perovskites and related materials #Rare-earth and actinide compounds #Solid-state spectroscopy and crystallography #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.68.134414
arxiv created 2002/05/20 · openalex publication_date 2003/10/08 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We have studied the phase diagram of La_1\ensuremath-xCaxMnO3 for 0.5<~x<~0.9 using neutron powder diffraction and magnetization measurements. At 300 K all samples are paramagnetic and single phase with crystallographic symmetry Pnma. As the temperature is reduced a structural transition is observed which is to a charge-ordered state only for certain x. On further cooling the material passes to an antiferromagnetic ground state with N'eel temperature TN that depends on x. For 0.8<~x<~0.9 the structural transformation occurs at the same temperature as the magnetic transition. Overall, the neutron-diffraction patterns were explained by considering four phase boundaries for which La_1\ensuremath-xCaxMnO3 forms a distinct phase: the charge-ordered phases at x=0.5 and x=2/3, the monoclinic and C-type magnetic structure at x=0.80--0.85, and the G-type magnetic structure at x=1. Between these phase boundaries the magnetic reflections suggest the existence of mixed compounds containing both phases of the adjacent phase boundaries.