Electric-Dipole Active Two-Magnon Excitation in ab Spiral Spin Phase of a Ferroelectric Magnet Gd_<0.7>Tb_<0.3>MnO_3(Condensed matter: electronic structure and electrical, magnetic, and optical properties)

概要

論文の詳細を見る
A broad continuum-like spin excitation (1-10meV) with a peak structure around 2.4meV has been observed in the ferroelectric ab spiral spin phase of Gd_<0.7>Tb_<0.3>MnO_3 by using terahertz (THz) time-domain spectroscopy. Based on a complete set of light-polarization measurements, we identify the spin excitation active for the light E vector only along the a-axis, which grows in intensity with lowering temperature even from above the magnetic ordering temperature but disappears upon the transition to the A-type antiferromagnetic phase. Such an electric-dipole active spin excitation as observed at THz frequencies can be ascribed to the two-magnon excitation in terms of the unique polarization selection rule in a variety of the magnetically ordered phases.
社団法人日本物理学会の論文
2008-12-15