Large-shift Raman scattering in insulating cuprate materials
Salamon, David Vigdor
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/29974
Description
Title
Large-shift Raman scattering in insulating cuprate materials
Author(s)
Salamon, David Vigdor
Issue Date
1994
Doctoral Committee Chair(s)
Klein, Miles V.
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
raman scattering
cuprate materials
Language
en
Abstract
This thesis describes the use of large-shift ordinary Raman techniques
to probe features near the charge-transfer gap in insulating cuprate materials,
including the T' phase materials (R2Cu04, R=Gd, Eu, Sm, Nd, Pr), T phase
La2Cu04, and 123 phase PrBa2Cu3Cu06 and YBa2Cu3Cu06+x· For all of these
materials, several features are observed near 12000 cm-1 (-1.5 eV) with A2g,
B1g, and A1g symmetry. At low temperatures, the largest feature with A2g
symmetry splits in all the insulating cuprates into three distinct peaks: a
strong main peak, and two weaker side-bands offset approximately 600 and
1500 cm-1 higher in energy respectively. A B1g feature coinciding in position
with the optical conductivity peak is observed in all the T' phase materials,
but not in the other insulators. An A1g peak is observed in Gd2Cu04 and
Eu2Cu04 40-50 cm-1 lower in energy than the main A2g peak, and in
YBa2Cu3Cu06 around 2400 cm-1 above the main A2g peak. All of these
features have unusual, temperature-dependent resonance behavior with the
incident photon energy, and they seem to weaken in YBa2Cu3Cu06+x as x
moves through the metal-insulator transition. Some residual A2g scattering
may remain in superconducting phases. We propose an explanation for
many of the above observations involving a copper d xy to d x2_Y2 orbital
transitions. In this picture, the main A2g peak is the d-d transition energy, the
first side-band results from coupled phonon scattering, and the second sideband
results from unusual coupled two-magnon scattering.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
