  We have studied the magnetodielectric and magnetoelastic coupling in
TbFe3(BO3)4 single crystals by means of capacitance, magnetostriction and Raman
spectroscopy measurements. The data reveal strong magnetic field effects on the
dielectric constant and on the macroscopic sample length which are associated
to long range magnetic ordering and a field-driven metamagnetic transition. We
discuss the coupling of the dielectric, structural, and magnetic order
parameters and attribute the origin of the magnetodielectric coupling to phonon
mode shifts according to the Lyddane-Sachs-Teller (LST) relation.
