Spin and lattice excitations in multiferroics

0485837 - FZÚ 2018 CZ eng D - Thesis
Skiadopoulou, Styliani
Spin and lattice excitations in multiferroics.
Univerzita Karlova, Matematicko-fyzikální fakulta. Defended: Praha. - Praha: Univerzita Karlova, 2017. 150 s.
R&D Projects: GA MŠMT(CZ) LH15122; GA ČR GA15-08389S
EU Projects: European Commission(XE) 607521 - NOTEDEV
Institutional support: RVO:68378271
Keywords : multiferroic * electromagnon * phonon
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)

The magnetoelectric excitations of the room-temperature multiferroic BiFeO3 were investigated down to 10 K. Among the previously reported, two new IR active spin excitatins were discovered. Moreover, polar phonons in BiFeO3 ceramics, as well as in a thin films were investigated up to 900 K. The novel double perovskite Pb2MnTeO6 was 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. Mn-doping results in increas of the Néel temperature, whereas Co-doping in decrease of the magnetic field value of the spin-flop transitions, at which the magnetoelectric coupling enhances. Spin excitations were observed in all Ni3-xBxTeO6 (B=Mn,Co) compounds.

Permanent Link: http://hdl.handle.net/11104/0280775