Low Energy Excitations in La1.2Sr1.8Mn2O7 investigated by ellipsometry.pdf (79.2 kB)

Low Energy Excitations in La1.2Sr1.8Mn2O7 investigated by ellipsometry

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journal contribution
posted on 21.09.2020 by Ocean Mercier, Robert Buckley, Harry Trodahl, C Bernhard, B Balakrishnan
The low-energy excitations of the bilayered manganite La1.2 Sr1.8 Mn2 O7 have been explored by spectral ellipsometry from two faces of a single crystal over the range from 0.006 to 0.6 eV. This compound is a paramagnetic insulator at ambient temperature, with a transition to a ferromagnetic metal below a Curie temperature (Tc) of 125 K. Both the ab -plane and c -axis temperature-dependent conductivities have been determined. Essentially no temperature-dependent behavior is observed above Tc although below Tc both the phonon and electronic contributions are strongly temperature sensitive. The highest-frequency phonons, especially those involving Mn-O bond stretching, split and show frequency changes consistent with structural results in the literature, and furthermore there is clear evidence of an increase in electron-phonon coupling at and below Tc. We interpret the temperature-dependent electronic spectral contribution in the light of recent calculations that indicate that a mixed phase exists in the doped manganites below Tc, with coexisting regions of an itinerant large-polaron phase and a localized small-polaron phase. © 2005 The American Physical Society.

History

Preferred citation

Mercier, O., Buckley, R., Trodahl, H., Bernhard, C. & Balakrishnan, B. (2005). Low Energy Excitations in La1.2Sr1.8Mn2O7 investigated by ellipsometry. Physical Review B, 72(21), 214437-1:5-. https://doi.org/10.1103/PhysRevB.72.214437

Journal title

Physical Review B

Volume

72

Issue

21

Publication date

01/01/2005

Pagination

214437-1:5

Publisher

American Physical Society (APS)

Publication status

Published

Contribution type

Article

Online publication date

29/12/2005

ISSN

1098-0121

eISSN

1550-235X

Article number

214437

Language

en

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