[ Pobierz całość w formacie PDF ]
Light Scattering
9 Q
In Solids VII
Crystal-Field
and Magnetic Excitations
Edited by M. Cardona and G. Gtintherodt
With Contributions by
M. Cardona, G. Gtintherodt, B. Hillebrands,
G. Schaack
With 96 Figures and 24 Tables
Springer
Professor Dr., Dres. h. c. Manuel Cardona
Max-Planck-lnstitut fiir Festk6rperphysik
Heisenbergstr. I
D-70569 Stuttgart, Germany
Professor Dr. Gernot Gtintherodt
2. Physikalisches Institut
Rheinisch-Westf'filische Technische Hochschule Aachen
Templergraben 55
D-52074 Aachen, Germany
ISSN 0303-4216
ISBN 3-540-66075-5 Springer-Verlag Berlin Heidelberg NewYork
Library of Congress Cataloging-in-PublicationData applied for.
Die Deutsche Bibliotbek - CIP-Einheitsaufnahme
Light scattering in solids. - Berlin; Heidelberg; New York; Barcelona; Hong Kong; London; Milan;
Paris; Tokyo: Springer
7. Crystal-field and magnetic excitations. - 2000
(Topics in applied physics; Vol. 75)
ISBN 3-540-66075-5
Tbis work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned,
specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction
on
microfilm or in any other way. and storage in data banks. Duplication of this publication or parts thereof is permitted
only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission
for use must always be obtained from Springer-Verlag. Violations are liable for prosecution under the German
Copyright Law.
O Springer-Verlag Berlin Heidelberg 2000
Printed in Germany
The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in
the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and
therefore free for general use.
Cover concept: Studio Ca[amar Steinen
Cover production:
design & production
GmbH, Heidelberg
Typesetting: Data conversion by Steingraeber Satztechnik GmbH, Heidelberg
SPIN: 10658627
57/3144/mf- 5 4 3 2 I 0 - Printed on acid-free paper
Preface
This volume is the seventh of a series (Topics in Applied Physics, Vols. 8, 50,
51, 54, 66, 68, 75) devoted to inelastic light scattering by solids, both as a
physical effect and as a spectroscopic technique.
The previous volume, Light Scattering in Solids VI (LSS VI) appeared in
1991, four years after the discovery of high-temperature superconductivity.
By the time it appeared, inelastic (Ra.man) light scattering had established
itself as one of the most powerful techniques for the investigation of electronic
excitations, magnons, phonons, and electron-phonon interaction in the new
high-temperature superconductors. Correspondingly, a chapter of LSS VI was
devoted to Raman scattering in high-temperature superconductors. In the
past eight years, and with the discovery of new families of high-To supercon-
ductors, Raman spectroscopy has continued to demonstrate its usefulness for
the investigation and characterization of this class of materials. New excit-
ing materials, such as fullerenes and carbon nanotubes, porous silicon, and
the colossal magnetoresistance manganates, as well as materials exhibiting
spin-Peierls transitions, have also shown to be excellent candidates for the
investigation by means of inelastic light-scattering spectroscopy. Progress in
instrumentation has extended the capabilites of Raman spectroscopy in the
directions of spatial microsampling and time-resolved spectroscopy. Increas-
ing commercial availability of laser-based equipment producing subpicosec-
ond pulses has led to the technique of "coherent phonons" which can be
considered equivalent to conventional spontaneous Raman scattering but in
the time instead of the frequency domain. A chapter devoted to coherent pho-
nons will appear soon in
Light Scattering in Solids VIII,
now in preparation.
This volume contains an introductory chapter with a review of the work
in previous volumes, a summary of the contents of the present one, a preview
of LSS VIII, and a survey of some of the progress in other aspects of Rama~
spectroscopy that has taken place since 1991.
Chapter 2 of this volume discusses electronic excitations between crystal
field split levels of transition-metal and rare-earth ions in crystals, among
them high-To superconductors. Chapter 3 is concerned with a wide range of
magnetic excitations that appear in superlattices containing magnetic metals.
The authors would like to thank once again Sabine Birtel for secretarial
help and skillful use of modern word processing techniques. Thanks are also
due to the Staff of Springer-Verlag, in particular Ms Friedhilde Meyer and
Dr. Werner Skolaut for unbureaucratic and skillful production of this volume.
Stuttgart and Aachen,
Manuel Cardona
August 1999
Gernot Giintherodt
Contents
1 Introduction ..............................................
1
M. Cardona and G. Gfintherodt
1.1 Survey of Previous Volumes (I-VI) .............................
1
1.1.1 Contents of
Light Scattering in Solids I ....................
1
1.1.2 Contents of
Light Scattering in Solids 1I ....................
2
1.1.3 Contents of
Light Scattering in Solids III ...................
2
1.1.4 Contents of
Light Scattering in Solids IV ...................
2
1.1.5 Contents of
Light Scattering in Solids V ....................
3
1.1.6 Contents of
Light Scattering in Solids VI ...................
3
1.2 Highlights and Recent Progress
in Raman Spectroscopy .......................................
4
1.3 Contents of This Volume ......................................
13
1.3.1 Chapter 2 ..............................................
13
1.3.2 Chapter 3 ..............................................
16
References .....................................................
20
2 Raman Scattering
by Crystal-Field Excitations
..................................
24
G.
Schaack
2.1 Introduction .................................................
24
2.2 Theory of Inelastic Light Scattering
by Electronic Transitions ..................................... 29
2.2.1 Basic Relations in Electronic Raman Scattering ............. 29
2.2.2 The Scattering Tensor ...................................
37
2.2.3 Selection Rules for Light Scattering
by Crystal-Field Excitations .............................. 39
2.2.4 Intensities .............................................. 44
2.2.5 Intra-configurational Raman Resonances ................... 52
2.2.6 Nonlinear Raman Spectroscopy ........................... 58
2.2.7 Raman Scattering in Magnetically Ordered Crystals ......... 61
2.2.8 Time Resolved Scattering ................................ 69
2.3 Effects of Localized Electron-Phonon Interaction ................. 72
2.3.1 Vibronic States .........................................
72
2.3.2 Jahn-Teller Effects ......................................
77
2.3.3 Resonant 4f-Electron-Phonon Interaction ..................
86
V I II Contents
2.4 Applications ................................................. 114
2.4.1 Crystal Field Levels in High-Tc Superconductors ............ I14
2.4.2 Crystal Field Studies in Ionic and Organometallic Crystals ... 128
2.4.3 Localized Excitations in Semimagnetic Semiconductors ....... 137
2.5 Conclusions .................................................
141
2.A Appendix ..................................................
143
2.A.1 Representations of the Scattering Tensor ...................
143
2.A.2 Selection Rules .........................................
145
References .....................................................
164
3 Brillouin Light Scattering
from Layered Magnetic Structures
...........................
174
Burkard Hillebrands
3.1 Introduction .................................................
174
3.2 Theoretical Background .......................................
177
3.2.1 Continuum Theory of Spin-Wave Excitations ...............
178
3.2.2 Magnetic Anisotropies ...................................
184
3.2.3 Spin Waves in Single Magnetic Layers ......................
191
3.2.4 Spin Waves in Magnetic Multilayers .......................
194
3.2.5 Nonlinear Excitations ....................................
200
3.3
The Light Scattering Cross Section .............................
200
3.4 Instrumentation .............................................
204
3.5 Selected Applications .........................................
208
3.5.1 Determination of Magnetic Anisotropies,
Reorientation Transitions ................................. 208
3.5.2 Perpendicularly Magnetized Films: Fe/Cu(001) .............. 223
3.5.3 Multilayered Structures With Dipolar Coupling ............. 224
3.5.4 Interlayer Exchange Coupling ............................. 232
3.5.5 Systems with Spatial Inhomogeneities ...................... 242
3.5.6 Light Scattering from Microwave Excited Spin Waves ........ 253
3.5.7 Spin Waves in Corrugated and Patterned Films .............
254
3.6 Conclusions and Outlook .....................................
256
References ....................................
.................
269
Index .........................................................
291
[ Pobierz całość w formacie PDF ]