This article is cited in 5 papers

Magnetism

Features of magnetic properties of La$_x$MnO$_{3+\delta}$ (0.815 $\le x\le$ 1.0)

T. N. Tarasenko^a, A. S. Mazur^a, A. I. Linnik^a, V. T. Dovgii^a, G. I. Makovetskii^b, K. I. Yanushkevich<sup>b

a</sup> Galkin Donetsk Institute for Physics and Engineering, Donetsk
^b Scientific-Practical Materials Research Centre of NAS of Belarus

Abstract: Magnetic and resonance studies of the system of polycrystalline samples of self-doped manganites La$_x$MnO$_{3+\delta}$ ($x$ = 0.815, 0.90, 0.94, 0.97, and 1.0) have been performed in a temperature range of 77–300 K. According to $^{55}$Mn NMR data, all samples contain a ferromagnetic phase at 77 K. As the defect density increases ($x$ changes from 1.0 to 0.815), samples become more magnetically ordered. In this case, the ferromagnetic state of the system gradually changes from a mixed state in which both ferromagnetic insulating (basic) and ferromagnetic metal (for $x$ = 0.97 and 1.0) phases coexist to only the ferromagnetic metal state (for $x$ = 0.815 and 0.90). It has been shown that both ferromagnetic metal and ferromagnetic insulating phases are inhomogeneous, and either phase consists of two phases with different dynamics of nuclear spins and different Curie temperatures. The diagram of the magnetic phase state of the La$_x$MnO$_{3+\delta}$ system ($x$ = 0.815, 0.90, 0.94, 0.97, 1.0) has been constructed for a temperature range of 120–240 K and Mn$^{4+}$ contents of 12–30%.

Received: 30.06.2010

 English version: Physics of the Solid State, 2011, 53:5, 957–963

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