Spin and Lattice Excitations in Multiferroics

The scientific significance of dynamical magnetoelectric coupling, combined with the eminent implication of its technological applications, prompted our investigation of spin and lattice excitations of a series of widely known, as well as entirely novel, multiferroic materials. The magnetoelectric excitations of the celebrated room temperature multiferroic BiFeO3 were investigated. Among the previously reported, two new infrared active spin excitations were discovered. Polar phonons in BiFeO3 ceramics, as well as in a thin film epitaxially grown on TbScO3 substrate, were investigated in a broad temperature range. The novel double perovskite Pb2MnTeO6 was prepared and described for the first time. Its crystal and magnetic structure classify it in the rare family of antipolar antiferromagnets. The spin-induced colossal magnetoelectric effect in Ni3TeO6 stimulated us to discover electromagnons in this material and to prepare and study Mn and Co doped samples. All Ni3-xBxTeO6 (B=Mn, Co) compounds present the non-centrosymmetric R3 space group symmetry, collinear antiferromagnetic spin structure, and spin-induced electric polarization below TN. . Mn-doping results in increase of the Néel temperature, whereas Co-doping in decrease of the magnetic field value of the spin-flop transition, at which the..