Second harmonic generation in the centrosymmetric antiferromagnet NiO.
In spite of the fact that inversion is a symmetry operation of both the crystalline and the magnetic lattice of NiO, second harmonic generation (SHG) has been observed below the Néel temperature. A spectroscopic study shows that the signal is due to combined magnetic-dipole and electric-dipole transitions between the (3d)(8) levels of the Ni(2+) ion in the crystal field. The SHG is resonant in both the incoming and the outgoing light waves and thus greatly enhanced. A quadratic coupling of the nonlinear polarization to the order parameter was found. This allows the investigation of individual domains.
Fiebig
M
M
Institut für Physik, Universität Dortmund, 44221 Dortmund, Germany.
Fröhlich
D
D
Lottermoser
T
T
Pavlov
V V
VV
Pisarev
R V
RV
Weber
H J
HJ