Submillimeter and far-infrared study of Gd2CuO4

Abstract Dielectric and magnetic properties of Gd2CuO4 single crystal were investigated by means of FIR reflectivity and submillimeter transmissivity measurements at temperatures 5 – 300 K. Besides the four known Eu optical phonon modes we observed unexpected phonon lines at 104, 136 and 577 cm−1, which could be caused by structural deformations in the T' phase. The observed behaviour of Cu AFMR mode confirms the existence of the weak ferromagnetic moment and testifies to the strong influence of the Cu-Gd exchange on the magnetic properties of Gd2CuO4.