Pressure-induced modifications of crystal and magnetic structure of oxygen deficient La<Subscript>0.7</Subscript>Sr<Subscript>0.3</Subscript>MnO<Subscript>3-d</Subscript> manganites

The crystal and magnetic structures of the oxygen deficient manganites La<Subscript>0.7</Subscript>Sr<Subscript>0.3</Subscript>MnO<Subscript>3-d< /Subscript> (d=0.15, 0.20) have been studied by means of powder neutron diffraction over the 0–5.2 GPa pressure and 10–290 K temperature ranges. La<Subscript>0.7</Subscript>Sr<Subscript>0.3</Subscript>MnO<Subscript>2.85 </Subscript> exhibits a coexistence of rhombohedral <InlineEquation ID="Equ1"> <EquationSource Format="TEX">$(R\bar {3}c)$</EquationSource> </InlineEquation> and tetragonal (I4/mcm) crystal structures and below T<Subscript>g</Subscript> ~ 50 K a spin glass state is formed. La<Subscript>0.7</Subscript>Sr<Subscript>0.3</Subscript>MnO<Subscript>2.80 </Subscript> exhibits a tetragonal (I4/mcm) crystal structure. Below T<Subscript>g</Subscript> ~ 50 K a phase separated magnetic state is formed, involving coexistence of C-type AFM domains with spin glass domains. In both compounds the crystal structure and magnetic states remain stable upon compression. The factors leading to the formation of different magnetic states in La<Subscript>0.7</Subscript>Sr<Subscript>0.3</Subscript>MnO<Subscript>3-d< /Subscript> (d = 0.15, 0.20) and their specific high pressure behavior, contrasting with that of the stoichiometric A<Subscript>0.5</Subscript>Ba<Subscript>0.5</Subscript>MnO<Subscript>3</Su bscript> (A = Nd, Sm) compounds showing pressure-induced suppression of the spin glass state and the appearance of the FM state, are analysed. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2007