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Existence of orbital polarons in ferromagnetic insulating La$_{1-x}$Sr$_x$MnO$_{3}$ (0.11$<x<$0.14) evidenced by giant phonon softening

K. -Y. Choi·P. Lemmens·G. Güntherodt·Yu. G. Pashkevich·V. P. Gnezdilov·P. Reutler·L. Pinsard-Gaudart·B. Büchner·A. Revcolevschi
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Abstract

We present an inelastic light scattering study of single crystalline (La$_{1-y}$Pr$_y$)$_{1-x}$Sr$_{x}$MnO$_3$ ($0\leq x\leq0.14$,$y=0$ and $x=1/8$,$0\leq y\leq0.5$). A giant softening up to 20 - 30 cm$^{-1}$ of the Mn-O breathing mode has been observed only for the ferromagnetic insulating (FMI) samples ($0.11\leq x \leq 0.14$) upon cooling below the Curie temperature. With increasing Pr-doping the giant softening is gradually suppressed. This is attributed to a coupling of the breathing mode to orbital polarons which are present in the FMI phase.

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K. -Y. Choi, P. Lemmens, G. Güntherodt, Yu. G. Pashkevich, V. P. Gnezdilov, P. Reutler, L. Pinsard-Gaudart, B. Büchner, A. Revcolevschi. 2004-01-12. Existence of orbital polarons in ferromagnetic insulating La$_{1-x}$Sr$_x$MnO$_{3}$ (0.11$<x<$0.14) evidenced by giant phonon softening. https://doi.org/10.1103/physrevb.71.174402

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