Signatures of electronic polarons in La$_{1-x}$Sr$_{1+x}$MnO$_4$ observed by electron energy-loss spectroscopy

R. Kraus; M. Schrade; R. Schuster; M. Knupfer; A. Revcolevschi; B. Büchner; J. Geck

doi:10.1103/PhysRevB.83.165130

paper

Signatures of electronic polarons in La $_{1 - x}$ Sr $_{1 + x}$ MnO $_{4}$ observed by electron energy-loss spectroscopy

arXiv:1103.0428 · doi:10.1103/PhysRevB.83.165130

Abstract

The dielectric properties of La $_{1 - x}$ Sr $_{1 + x}$ MnO $_{4}$ single crystals with x = 0, 0.125, 0.25, and 0.5 were studied by means of electron energy-loss spectroscopy as a function of temperature and momentum transfer. A clear signature of the doped holes is observed around 1.65 eV energy loss, where spectral weight emerges with increasing x. For all $x \neq = 0$ , this doping-induced excitation can propagate within the ab-plane, as revealed by a clear upward dispersion of the corresponding loss peak with increasing momentum transfer. The hole-induced excitation also shifts to higher energies with the onset of magnetic correlations for x = 0.5, implying a strong coupling of charge and spin dynamics. We conclude that (i) the loss feature at 1.65 eV is a signature of electronic polarons, which are created around doped holes, and that (ii) this low-energy excitation involves the charge transfer between manganese and oxygen. The finite dispersion of these excitations further indicates significant polaron-polaron interactions.

7 pages, 4 figures

Signatures of electronic polarons in La $_{1 - x}$ Sr $_{1 + x}$ MnO $_{4}$ observed by electron energy-loss spectroscopy

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Signatures of electronic polarons in La1−x​Sr1+x​MnO4​ observed by electron energy-loss spectroscopy

Abstract

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Cited by in corpus (2)

Signatures of electronic polarons in La $_{1 - x}$ Sr $_{1 + x}$ MnO $_{4}$ observed by electron energy-loss spectroscopy