Terahertz-infrared spectroscopy of single crystalline m-type hexaferrite BaTi_xFe_(12-x)O_(19)

摘要

We have studied polarization-dependent broad-band dielectric response of single-crystalline Ti-substituted barium hexaferrites BaTi_xFe_(12-x)O_(19), x=0.64., 0.75, 1.1, in the frequency range from 10 to 8000 cm~(-1) and at temperatures from 5 to 300 K. In addition to a rich set of phonon resonances located at frequencies from 90 to 800 cm~(-1) we observed an unusual low-energy response (terahertz region, 10-100 cm~(-1)) stemming from two different effects: relaxational process and second order spin-orbit coupling in Fe~(2+) ground state, that may set up new prospects for doped hexaferrites in terahertz technologies.