High pressure effects on the crystal and magnetic structure ofPr1−xSrxMnO3 manganites(x = 0.5–0.56)

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The crystal and magnetic structures of the manganitesPr1−xSrxMnO3 (x = 0.5, 0.56) have been studied by means of powder neutron diffractionat high external pressures up to 4.8 GPa. At ambient pressure bothPr0.44Sr0.56MnO3 andPr0.5Sr0.5MnO3 have a tetragonalstructure (space group I4/mcm). At K in Pr0.44Sr0.56MnO3 the onset of A-type antiferromagnetic (AFM) state occurs, which is accompaniedby a structural phase transformation to the orthorhombic structure (spacegroup Fmmm). Pr0.5Sr0.5MnO3 at 175 K<T<TC = 265 K exhibits an intermediate tetragonal ferromagnetic (FM) phase followed by theonset of the orthorhombic A-type AFM phase at K. Under high pressure, in Pr0.44Sr0.56MnO3 a tetragonal C-type AFM phase ( K) appears and the phase separated state is formed, consisting of its mixturewith the initial orthorhombic A-type AFM phase ( K). In Pr0.5Sr0.5MnO3 the application of high pressure leads to a noticeable increase of the FM–A-type AFMtransition temperature from up to 230 K and formation of a phase separated state below 150 K, consisting ofa mixture of orthorhombic A-type AFM phase and tetragonal phase withoutlong range magnetic order. The stability of different magnetic states ofPr0.44Sr0.56MnO3 and Pr0.5Sr0.5MnO3 under high pressure is discussed.