Multiferroic hexagonal HoMnO_1tn3 films [Elektronische Ressource] / von Jong-Woo Kim

Multiferroic hexagonal HoMnO lms3Von der Fakult at MaschinenwesenderTechnischen Universit at DresdenzurErlangung des akademischen GradesDoktoringenieur (Dr.-Ing.)angenommene DissertationvonM.Sc. Jong-Woo Kimgeboren am 21. Mai 1977in Chun-Cheon, Sud-Korea20091. Gutachter: Prof. Dr. Ludwig Schultz (TU Dresden)2. Gutachter: Prof. Dr. Manfred Fiebig (Universit at Bonn)Tag der Einreichung: 29.07.2009Tag der Verteidigung: 22.12.2009AbstractThe fundamental properties of hexagonal multiferric HoMnO lms have been thor-3oughly investigated. The lms are grown by pulsed laser deposition on Y:ZrO (111)2substrates. High quality epitaxial HoMnO lms of 25 { 1000 nm thickness were3successfully prepared. The lm properties are compared to those of single-crystals.The magnetization measurements revealed that the lms show a deviating magneticbehavior from the single-crystals in several ways. For instance, the lms have a3+weakened antiferromagnetic Ho order con rmed from magnetic susceptibility. Thedi erences are likely to be related to the modi ed (mostly larger) lattice parametersof lms. An approximate phase diagram in comparison with the single-crystal’sone is constructed. For multiferroicity investigations, Second Harmonic Generation(SHG; in collaboration with the group of M. Fiebig) has been employed. By SHG,the ferroelectric polar order of the lms is obviously con rmed.