S. V. Trukhanov

Magnetic state of the structural separated anion-deficient La0.70Sr0.30MnO2.85 manganite

The results of neutron diffraction studies of the La0.70Sr0.30MnO2.85 compound and its behavior in an external magnetic field are stated. It is established that in the 4–300 K temperature range, two structural perovskite phases coexist in the sample, which differ in symmetry (groups

Investigation of stability of ordered manganites

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The influence of oxygen deficiency on the magnetic and electric properties of La0.70Ba0.30MnO3 −γ (0≤γ≤0.30) manganite with a perovskite structure

and I4/mcm). The reason for the phase separation is the clustering of oxygen vacancies. The temperature (4–300 K) and field (0–140 kOe) dependences of the specific magnetic moment are measured. It is found that in zero external field, the magnetic state of La0.70Sr0.30MnO2.85 is a cluster spin glass, which is the result of frustration of Mn3+-O-Mn3+ exchange interactions. An increase in external magnetic field up to 10 kOe leads to fragmentation of ferromagnetic clusters and then to an increase in the degree of polarization of local spins of manganese and the emergence of long-range ferromagnetic order. With increasing magnetic field up to 140 kOe, the magnetic ordering temperature reaches 160 K. The causes of the structural and magnetic phase separation of this composition and formation mechanism of its spin-glass magnetic state are analyzed.

Magnetic properties of the FeIn2S4 ternary-compound crystals

AbstractThe results of experimental investigation of the chemical phase composition, crystal structure, and magnetic properties of the manganite La0.70Sr0.30MnO3−γ (0 ≤ γ ≤ 0.25) with perovskite structure depending on the concentration of oxygen vacancies are presented. It is found that the mean grain size of the stoichiometric solid solution of La0.70Sr0.30MnO3 amounts approximately to 10 μm, while the grain size for anion-deficient solid solutions of La0.70Sr0.30MnO3−γ is approximately 5 μm. It is found that samples with 0 ≤ γ ≤ 0.13 have a rhombohedral unit cell (with space group n

Crystal structure and magnetic properties of Ba-ordered manganites Ln0.70Ba0.30MnO3−δ (Ln = Pr, Nd)

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Magnetic and absorbing properties of M-type substituted hexaferrites BaFe12–xGaxO19 (0.1 < x < 1.2)

n, Z = 2), while samples with γ ≥ 0.20 have a tetragonal unit cell (space group I4/mcm, Z = 2). It is proved experimentally that the magnetic phase state of the manganite La0.70Sr0.30MnO3−γ changes upon a decrease in the oxygen content. It is shown that anion-deficient solid solutions of La0.70Sr0.30MnO3−γ experience a number of successive magnetic phase transformations in the ground state from a ferromagnet (0 ≤ γ ≤ 0.05) to a charge-disordered antiferromagnet (γ = 0.25) via an inhomogeneous magnetic state similar to a cluster spin glass (0.13 ≤ γ ≤ 0.20). The mean size of ferromagnetic clusters (r ≈ 50 nm) in the spin glass state is estimated. It is shown that oxygen vacancies make a substantial contribution to the formation of magnetic properties of manganites. The generalized magnetic characteristics are presented in the form of concentration dependences of the spontaneous magnetic moment, coercive force, and the critical temperature of the magnetic transition. The most probable mechanism of formation of the magnetic phase state in Sr-substituted anion-deficient manganites is considered. It is assumed that in the absence of orbital ordering, a decrease in the magnetic ion coordination number leads to sign reversal in indirect superexchange interactions Mn3+-O-Mn3+.