Very weak electron-phonon coupling and strong strain coupling in manganites

Abstract

The coupling of the manganite stripe phase to the lattice and to strain has been investigated via transmission electron microscopy studies of polycrystalline and thin film manganites. In polycrystalline \PCMOfiftwo a lockin to $q/a^{\ast }=0.5$ in a sample with $x>0.5$ has been observed for the first time. Such a lockin has been predicted as a key part of the Landau CDW theory of the stripe phase. Thus it is possible to constrain the size of the electron-phonon coupling in the CDW Landau theory to between 0.04% and 0.05% of the electron-electron coupling term. In the thin film samples, films of the same thickness grown on two different substrates exhibited different wavevectors. The different strains present in the films on the two substrates can be related to the wavevector observed via Landau theory. It is demonstrated that the the elastic term which favours an incommensurate modulation has a similar size to the coupling between the strain and the wavevector, meaning that the coupling of strain to the superlattice is unexpectedly strong.

6 pages, 7 figures

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Cited by in corpus (6)

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• New phase transition in $P{r}_{1-x}C{a}_{x}Mn{O}_3$ system: evidence for electrical polarization in charge ordered manganites
• Bending and Breaking of Stripes in a Charge-Ordered Manganite
• Charge density waves enhance the electronic noise of manganites
• Origin of Low-Energy Excitations in Charge-Ordered Manganites
• Response of acoustic phonons to charge and orbital order in the 50\% doped bilayer manganite LaSr${}_2$Mn${}_2$O${}_7$