https://doi.org/10.1007/s100510170266
Quantum theory of the magneto-optical effect and magnetization of Nd-substituted yttrium iron garnet
1
Department of Physics, Luoyang Teacher's College, Luoyang 471022,
PR China
2
China Center of Advanced Science and Technology (World Laboratory), PO Box
8730, Beijing 100080, China and Department of Physics, Nanjing University,
Nanjing 210008, PR China
3
China Center of Advanced Science and Technology (World Laboratory), PO Box
8730, Beijing 100080, China and Department of Physics, Luoyang Teacher's
College, Luoyang 471022, PR China
4
Laboratoire des Champs Magnetiques Intenses, CNRS/MPI, BP 166, 38042
Grenoble, France
Corresponding author: a mguillot@labs.polycnrs-gre.fr
Received:
8
November
2000
Published online: 15 March 2001
The magneto-optical and magnetic properties of Nd ions in Y
Fe
O
garnet are analyzed by using
quantum theory. In the spontaneous state, the magneto-optical effects
originate mainly from the intra-ionic electric dipole transitions between
the 4
and 4
states split by the spin-orbit,
crystal field, and superexchange interactions. For the excited
configuration, the coupling scheme of Yanase is extended to the Nd
ion. The magneto-optical resonance frequencies are mainly determined by
the splitting of the 5d states induced by the crystal field. The theoretical
results of both Nd magnetization and Faraday rotation are in good agreement
with experiments. The observed Faraday rotation is proved to be of the
paramagnetic type. Although the value of the magneto-optical resonance
frequency derived from a macroscopic analysis is approximately confirmed by
our theoretical study, a new assignment about the transitions associated
with this resonance is unambiguously determined. The spin-orbit coupling of
the ground configuration has a great influence on both the Faraday rotation
and magnetization, but, unlike the theoretical results obtained in some
metals and alloys, the relation between the Faraday rotation and the
spin-orbit coupling strength is more complex than a linear one. The
magnitude of the magneto-optical coefficient increases as the spin-orbit
interaction strength of the ground configuration decreases when the strength
is not very weak. Finally, the temperature dependence of the
magneto-optical coefficient and the effect of the mixing of different
ground-term multiplets induced by the crystal field are analyzed.
PACS: 78.20.Ls – Magnetooptical effects / 75.50.Gg – Ferrimagnetics
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2001