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3 papers
Magnetism
X-ray emission studies of evolution of the electron and spin structures of Mn in mixed manganites Ln$_{1-x}$Sr$_x$MnO$_3$ (Ln = La, Sm, and Ce)
A. E. Sovestnova,
B. T. Melekhb,
V. V. Fedorovac,
È. V. Fomina a The Petersburg Nuclear Physics Institute, The National Research Center "Kurchatov Institute"
b Ioffe Institute, St. Petersburg
c Peter the Great St. Petersburg Polytechnic University
Abstract:
The chemical shift
$\Delta E_{K\beta1}$ and the exchange splitting
$\Delta E_{\mathrm{split}}$ of the emission X-ray Mn
$K_{\beta1}$ line in mixed manganites
Ln$_{1-x}$Sr
$_x$MnO
$_3$ (
Ln = La, Sm, and Ce) have been systematically studied for the first time. It has been found that
$\Delta E_{K\beta1}$ and
$\Delta E_{\mathrm{split}}$ are almost the same in the range
$x <$ 0.4–0.5, as is the case in Mn
$_2$O
$_3$, and then they decrease relatively quickly to the values characteristic of MnO
$_2$. It has been assumed that such a behavior corresponds to the model where in the region of hole doping (
$x <$ 0.5), the ground state is a mixture of configurations Mn
$^{3+}$ 3
$d^4$ and 3
$d^4\underline{L}$, so that the second configuration fraction increases with
$x$. At high values of
$x$, the configuration Mn
$^{4+}$ 3
$d^3$ should be taken into account; the contribution of this configuration increases with increasing degree of doping, and it becomes dominant at
$x$ = 1. In all cases, the manganese state is high-spin.
Received: 19.07.2011
Accepted: 30.09.2011
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