X-ray study of Nd0.5Sr0.5MnO3 manganite structure above and below the ferromagnetic metal-antiferromagnetic insulator spontaneous phase transition

The crystal structure of the manganite Nd0.5Sr0.5MnO3 is studied at tempera ture T=300 and 77.3 K by means of an x-ray diffractometer. It is shown that the transition from the ferromagnetic metallic state to the antiferromagne tic insulating charge-ordered state is accompanied by a lowering of the sym metry of the structure from orthorhombic to monoclinic. The space-group sym metry of the orthorhombic and monoclinic phases is identified as Imma and P 2(1)/m, respectively. Twinning of the crystal and the formation of a twin d omain structure with coherent boundaries in the (00l) crystallographic plan es are found. (C) 2001 American Institute of Physics.