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The crystal and magnetic structures of hexagonal manganites YMnO3 and LuMnO3 have been studied by powder neutron diffraction up to 6 GPa in the temperature range of 10-300 K. At ambient pressure, a triangular antiferromagnetic (AFM) state of a Γ1 irreducible representation is stable below TN=70 K in YMnO3. Upon application of high pressure, a spin-reorientation was observed and the triangular AFM structure evolves from Γ1 to Γ1+Γ2 representation symmetry. In LuMnO3, the triangular AFM state of a Γ2 symmetry with TN ≈ 95 K remains stable in the investigated pressure range. The ordered Mn magnetic moment is suppressed at high pressure and low temperature, with much more pronounced effects for YMnO3, indicating enhanced spin fluctuations due to stronger magnetic frustration of the triangular lattice under higher pressure. The relationship between the evolution of spin fluctuations and in-plane Mn-O bonds under pressure is analyzed. [ABSTRACT FROM AUTHOR]

The magnetic and crystal structures of anion-deficient La0.7Sr0.3MnO3− d manganites ( d = 0.15 and 0.20) are studied by neutron diffraction in the range of high pressures 0–5 GPa and temperatures 10–300 K. It is found that a spin-glass state forms in La0.7Sr0.3MnO2.85 below T g ∼ 50 K, while magnetic phase separation is observed in La0.7Sr0.3MnO2.80, which is characterized by the coexistence of AFM domains of the C type with spin-glass domains. As distinct from the stoichiometric A0.5Ba0.5MnO3 manganites (A = Nd, Sm), in which the high-pressure effect suppresses the spin-glass state and gives rise to ferromagnetism, the spin-glass state in La0.7Sr0.3MnO2.85 is stable under pressure. The bulk modulus of La0.7Sr0.3MnO2.85 is considerably smaller than that for the stoichiometric La0.7Sr0.3MnO3 compound. The causes of the formation of different types of the magnetic structure in La0.7Sr0.3MnO3− d ( d = 0.15 and 0.20) and different high-pressure effects on the magnetic structure of stoichiometric and anion-deficient manganites are analyzed. [ABSTRACT FROM AUTHOR]

A crystal and magnetic structure of manganites Pr 0.7 Ca 0.3 Mn 1- y Fe y O 3 ( y  = 0, 0.1) has been studied by means of powder neutron diffraction at pressures up to 4 GPa in the temperature range 15-300 K. Under high pressure, an appearance of A-type antiferromagnetic state in both systems was observed. Both compounds exhibit anisotropic compression of the lattice which leads to the apical compression of MnO 6 octahedra along the crystallographic b -axis. The calculated from obtained structural data pressure dependence of the charge-carrier bandwidth is in a qualitative agreement with observed pressure behavior of insulator-metal transition temperature within the framework of the double-exchange model. [ABSTRACT FROM AUTHOR]

The crystal and magnetic structure of a manganite La 0.7 Sr 0.3 Mn 0.83 Nb 0.17 O 3 have been studied by means of a neutron diffraction method at pressures up to 4.5 GPa and in temperature range 4–290 K. At ambient pressure and temperature below T C = 150 K a ferromagnetic FM state is stabilized in this compound. At pressures P ≥ 1.5 GPa and temperature below T N ∼110 K appearance of a new A-type antiferromagnetic AFM phase in La 0.7 Sr 0.3 Mn 0.83 Nb 0.17 O 3 has been observed. A further pressure increasing leads to an increase in the volume fraction of the A-type antiferromagnetic AFM phase, which coexists with the suppressed ferromagnetic phase in the whole experimental pressure range. The Curie and Néel temperature increase upon lattice contraction with comparable pressure coefficients dT C /dP = 2.1 K/GPa and dT N /dP = 1.6 K/GPa. The structural mechanisms of the changes in magnetic structure of La 0.7 Sr 0.3 Mn 0.83 Nb 0.17 O 3 manganite are discussed. [ABSTRACT FROM AUTHOR]

The crystal and magnetic structure of nanostructured manganites La 0.63 Sr 0.37 MnO 3 and La 0.72 Sr 0.28 MnO 3 has been studied by means of a neutron diffraction method in the pressure range 0–4.5 GPa and the temperature range 5–300 K. In both samples the FM ordering is formed close above the room temperature and at cooling below T < 270 K the ferromagnetic FM phase coexists with an A-type antiferromagnetic AFM phase. At high pressures the volume fraction of AFM phase increases, while FM is gradually suppressed. The structural aspects of the magnetic phase separation and pressure effects on the studied nanostructured manganites are discussed. [ABSTRACT FROM AUTHOR]

The crystal and magnetic structure of the nanostructured manganite La 0.53 Sr 0.47 MnO 3 has been studied using the neutron diffraction method in the pressure range 0–5.5 GPa and the temperature range 15–300 K. At ambient pressure, the ferromagnetic ordering in the studied compound is formed below T ≈ 335 K. With an increase of the pressure above 2.1 GPa and cooling below T < 250 K, an A-type antiferromagnetic phase appears, which coexists with the initial ferromagnetic one. Further increase of the pressure leads to the growth of the volume fraction of the antiferromagnetic phase, while the ferromagnetic ordering is gradually suppressed. The structural origins of the pressure-induced magnetic phase separation in the nanostructured manganites are discussed. • The structure of nanomanganite La0.53Sr0.47MnO3 at high pressure have been studied. • The FM ordering in this compound was formed at ambient pressure, below T ≈ 335K. • At P ≥ 2.1 GPa and T < 250 K, the coexistence of FM and A-type AFM phase was found. • The structural separation was discussed in the framework of the "core-shell" model. • The most important parameters of crystal and magnetic structures were calculated. [ABSTRACT FROM AUTHOR]

The high-pressure evolution of structural and magnetic properties of the single valence Mn3+ manganite La 0.8 Sr 0.2 Mn 0.9 Sb 0.1 O 3 was studied by means of neutron powder diffraction up to 4.5 GPa in the temperature range of 10–300 K. At ambient pressure, a ferromagnetic ground state with the magnetic ordering temperature T C ≈ 175 K is stabilized. Application of high pressure suppresses the initial FM phase and leads to the appearance of a new A-type antiferromagnetic AFM phase with T N ~ 130 K at P = 2.2 GPa. Under compression, both T C and T N almost linearly increases with the pressure coefficient of 1.9(2) and 0.9(3) K/GPa, respectively. It is assumed that the appearance of the A-type AFM state is mediated by the strong anisotropic distortions of MnO 6 octahedra, coupled to the e g d x 2 - z 2 orbital polarization at high pressures. [ABSTRACT FROM AUTHOR]