  We investigate the change of magnetic moments of octet baryons in nuclear
matter at a finite density and temperature. Quark-meson coupling models are
employed in describing properties of octet baryons and their interactions.
Magnetic moments of octet baryons are found to increase non-negligibly as
density and temperature increase, and we find that temperature dependence can
be strongly correlated with the quark-hadron phase transition. Model dependence
is also examined by comparing the results from the quark-meson coupling (QMC)
model to those by the modified QMC (MQMC) model where the bag constant is
assumed to depend on density. Both models predict sizable dependence on density
and temperature, but the MQMC model shows a more drastic change of magnetic
moments. Feasible changes of the nucleon mass by strong magnetic fields are
also reported in the given models.
