Alexander von Humboldt Foundation Conference
«Technologies of the 21st century: biological, physical, informational and social aspects»
Saint-Petersburg, Russia, September 27-29, 2005
LINEAR AND NONLINEAR OPTICAL SPECTROSCOPY
OF MULTIFERROIC MATERIALS
R.V. Pisarev
Ioffe Physico-Technical Institute of Russian Academy of Sciences, St. Petersburg, Russia
Multiferroic materials were discovered in the 1960s and created a lot of excitement
because the crosslink between magnetic, electric, ferroelectric, and elastic properties.
However, original efforts to develop new devices failed due to the smallness of the relevant
susceptibilities and effects. At present, a startling revival of interest in multiferroic materials
is observed because new materials and heterostructures have been discovered and developed.
In this talk we report on the study of electronic and magnetic structures in several
groups of 3d transition-metal multiferroic materials using linear and nonlinear optical
spectroscopy [1]. The main experimental methods used are polarized optical absorption,
variable angle spectroscopic ellipsometry, and second harmonic generation (SHG).
Experiments were done in a wide spectral range from 0.5 to 5.4 eV, at temperatures from 2 to
300 K, and in magnetic fields up to 7 T.
The following materials and topics are discussed in the paper:
1. Ferroelectriс antiferromagnetic hexagonal manganites RMnO3 (R=Sc, Y, In, Ho- Lu),
where a new type of SHG susceptibility was discovered and allowed us to study magnetic
structures and phase diagrams of these materials that were a controversial issue for several
decades [2].
2. Noncentrosymmetric copper borate CuB2O4 where three types of magnetic-field-induced
second harmonic (MFISH) generation are observed and provide selective access to
nonequivalent copper sublattices [3].
3. Noncentrosymmetric gadolinium-iron borate GdFe3(BO3)4 where we prove for the first
time possibility of phase matching for SHG in magnetic materials [4].
4. A new type of magnetoelectric coupling was observed in YMnO3 [5]. We explain this
phenomenon by piezomagnetic interaction of ferroelectric and antiferromagnetic order
parameters within domain walls [6].
5. Piezoelectric ferrimagnet GaFeO3, where we studied electronic structure, Faraday
rotation, and second harmonic generation [7].
[1] M. Fiebig, V. V. Pavlov, and R. V. Pisarev, J. Opt. Soc. Amer. B 22, 96 (2005).
[2] D. Fröhlich, K. Kohn, St. Leute, Th. Lottermoser, V.V. Pavlov, and R.V. Pisarev, Phys.
Rev. Lett. 84, 5620 (2000).
[3] R. V. Pisarev, I. Sänger, G. A. Petrakovskii, and M. Fiebig, Phys. Rev. Lett. 93, 037204
(2004).
[4] A. M. Kalashnikova, V. V. Pavlov, R. V. Pisarev, L. N. Bezmaternyukh, and Th. Rasing,
JETP Lett. 80, 293 (2004).
[5] M. Fiebig, Th. Lottermoser, D. Fröhlich, A.V. Goltsev, and R.V. Pisarev, Nature
(London) 419, 818 (2002).
[6] A. V. Goltsev, R. V. Pisarev, Th. Lottermoser, and M. Fiebig, Phys. Rev. Lett. 90, 177204
(2003).
[7] A. M. Kalashnikova, R. V. Pisarev, L. N. Bezmaternyukh, et al. (submitted).
R.V. Pisarev
pisarev@mail.ioffe.ru