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Substrate-controlled nucleation of the magnetic phase transition in nanostructures
Hajduček, Jan ; Procházka, Pavel (referee) ; Uhlíř, Vojtěch (advisor)
Properties of the phase transition in iron-rhodium (FeRh) from the antiferromagnetic (AF) to ferromagnetic phase (FM) are largely affected by lattice defects in FeRh. Epitaxial layers of FeRh are grown on monocrystalline MgO (001) substrates. Surface atomic terraces of the substrate can induce defects in epitaxial layers and modify electronic and magnetic properties. In this thesis the effect of surface atomic terraces on the width and the hysteresis of the metamagnetic phase transition in FeRh thin layers and nanostructures is studied. The amount and character of defects in FeRh are also affected by mutual orientation of terraces and FeRh nanowires, which changes the number of discrete jumps in FM-AF transition. The nanowires have been fabricated by electron-beam lithography. FM domains in in FeRh have been observed by magnetic force microscopy and electrical transport properties of differently oriented nanowires have been studied by 2-probe measurements. Higher density of surface atomic terraces significantly increases the number of discrete jumps in the FM-AF transition.
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Deposition of low-damping metamagnetic thin films
Hnilica, Ján ; Vaňatka, Marek (referee) ; Uhlíř, Vojtěch (advisor)
Properties of magnetic damping in the FeRh alloy are determined by stoichimetric ratio of individual components of the alloy, by the number of structural defects, and rate of epitaxy of thin films deposited on MgO(001) substrates. This thesis describes the mechanism of each contribution to magnetic damping and clarifies the influence of stoichimetric ratio, structural defects, and epitaxy on the resulting magnetic damping. FeRh thin films were deposited using magnetron sputtering and characterized via vibrating sample magnetometry. Magnetic damping was evaluated using broadband ferromagnetic resonance. The magnetic damping significantly increases with increasing amount of Rh atoms in the alloy, decreasing rate of epitaxy, and increasing number of structural defects.
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Deposition of low-damping metamagnetic thin films
Hnilica, Ján ; Vaňatka, Marek (referee) ; Uhlíř, Vojtěch (advisor)
Properties of magnetic damping in the FeRh alloy are determined by stoichimetric ratio of individual components of the alloy, by the number of structural defects, and rate of epitaxy of thin films deposited on MgO(001) substrates. This thesis describes the mechanism of each contribution to magnetic damping and clarifies the influence of stoichimetric ratio, structural defects, and epitaxy on the resulting magnetic damping. FeRh thin films were deposited using magnetron sputtering and characterized via vibrating sample magnetometry. Magnetic damping was evaluated using broadband ferromagnetic resonance. The magnetic damping significantly increases with increasing amount of Rh atoms in the alloy, decreasing rate of epitaxy, and increasing number of structural defects.
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Substrate-controlled nucleation of the magnetic phase transition in nanostructures
Hajduček, Jan ; Procházka, Pavel (referee) ; Uhlíř, Vojtěch (advisor)
Properties of the phase transition in iron-rhodium (FeRh) from the antiferromagnetic (AF) to ferromagnetic phase (FM) are largely affected by lattice defects in FeRh. Epitaxial layers of FeRh are grown on monocrystalline MgO (001) substrates. Surface atomic terraces of the substrate can induce defects in epitaxial layers and modify electronic and magnetic properties. In this thesis the effect of surface atomic terraces on the width and the hysteresis of the metamagnetic phase transition in FeRh thin layers and nanostructures is studied. The amount and character of defects in FeRh are also affected by mutual orientation of terraces and FeRh nanowires, which changes the number of discrete jumps in FM-AF transition. The nanowires have been fabricated by electron-beam lithography. FM domains in in FeRh have been observed by magnetic force microscopy and electrical transport properties of differently oriented nanowires have been studied by 2-probe measurements. Higher density of surface atomic terraces significantly increases the number of discrete jumps in the FM-AF transition.
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Study of the structure and of interaction with gas molecules of Rh-Sn and Rh-SnO2
Janeček, Petr ; Nehasil, Václav (advisor) ; Jirka, Ivan (referee) ; Bartoš, Igor (referee)
In this work we present the results of the analysis of the surface structures and absorption properties with respect to the CO and O2 molecules of the Sn/Rh and Rh/SnO2 model systems. In the part dedicated to the Sn structures on Rh surfaces with two different orientations - Rh(110) and Rh(111) - we have investigated the development of the core electron levels and valence band during the development of surface reconstructions and absorption of CO molecules. The surface reconstructions of the Sn/Rh(110) systems were studied for the first time. Difference in behaviour w.r.t. Sn/Rh(111) was observed and explanation offered. Finally, on in-situ prepared epitaxial SnO2 layers, the surface reconstruction (4×1) was observed. The CO adsorp- tion properties of Rh on polycrystalline and epitaxial SnO2 layers were also studied and difference in behaviour explained.
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