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New magnetic state of intermetallics - parimagnetism - in RCo2-type compound
Šebesta, Jakub ; Prchal, Jiří (advisor) ; Prokleška, Jan (referee)
A sample of TmCo2 compound was prepared and studied by means of temperature dependence of an electric resistivity, specific heat, magnetisation and AC magnetic susceptibility, all in ambient pressure. We have observed anomalies in the temperature dependence of specific heat at the temperatures TC Tm = (3,60 ± 0,05) K and TC Co = (4,6 ± 0,1) K, which are in the agreement with anomalies in the data of other physical variables. By comparison with HoCo2 and ErCo2 compounds, there was made a suggestion, that the characteristic temperatures correspond to the magnetic order of the Tm and Co sub-lattices. After that, temperature dependencies of AC magnetic susceptibility under external hydrostatic pressures up to 3 GPa were measured. We observed anomalies mentioned above in the measured data and moreover one more anomaly around 35 K. This anomaly corresponds most probably to the flipping temperature Tf of the magnetisation of Co clusters through the plain perpendicular to the magnetic moment of the nearest rare-earth atom. From the set of the realized pressure points we estimated pressure coefficients for the characteristic temperatures ∂TC Tm /∂p = (0,40±0,02) K·GPa-1 and ∂Tf/∂p ~ 0 K·GPa-1, . Roughly zero values of coefficients are significant, because of comparison with other RCo2-type compound.
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Consequences of applying the hydrostatic pressure on the structural jump in RTAl compounds
Doležal, Petr ; Prchal, Jiří (advisor) ; Javorský, Pavel (referee)
Title: Consequences of applying the hydrostatic presure on the structural jump in RTAl compounds Author: Petr Doležal Department: Department of Condensed Matter Physics Supervisor: RNDr. Jiří Prchal, PhD., Department of Condensed Matter Physics Abstract: This bachelor thesis investigates the effects of hydrostatic pressure on structural transition in GdNiAl compound (ZrNiAl-type of structure), which have not been studied yet. This structural transformation represents an existence of a range of forbidden values of the lattice parameters ratio c/a, which cannot be adopted by compounds crystallizing in this type of structure. It prefers rather a step-like change of the parameters a and c. An anomalous behavior of resistivity, which appears in the area of the transition, was used for the structural transition determination. The results are accompanied by measurements of electrical resistivity at ambient pressure. Measurements on a polycrystalline sample suggested an anomalous behavior depicting the pressure dependence of the structural transition temperature. The pressure evolution of the structural transition temperature of a virgin sample is decreasing, being a consequence of higher sensitivity of the lattice constant c. Repeating the same experiment on the same piece of sample - i.e. sample with the...
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Influence of the external pressure on the magnetic behavior of the material
Valenta, Jaroslav ; Prchal, Jiří (advisor) ; Prokleška, Jan (referee)
This thesis deals with magnetic properties of the HoCo2 compound, which is composed of rare earth and transition metal elements. The study is focused on properties at ambient pressure and changes of the magnetic behavior of the material under hydrostatic pressure. At the ambient pressure, there was performed analysis of the sample quality with a finding of presence of three magnetic transitions: flipping temperature magnetization of Co clusters Tf = (125 ± 1) K, Curie temperature TC = (79,5 ± 0,1) K and spin-reorientation temperature TR = (16,4 ± 0,5) K. When applying the hydrostatic pressure up to 3 GPa, there was observed a shift of the temperatures of the magnetic transitions and in the case Tf and TR their consequent vanishing. From the shifts of the TC and Tf towards lower temperatures and from the vanishing of the Tf, it was concluded that Co magnetism is being suppressed by the influence of the hydrostatic pressure.
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Design of residential house
Moravcová, Eva ; Loudil, Lukáš (referee) ; Zich, Miloš (advisor)
This is a residential house in Brno. The supporting structure is reinforced concrete. The building has one basement and six floors. Vertical load-bearing structures are made up of reinforced concrete columns and walls. Horizontal load-bearing structures are formed by slabs (bearing in both directions). The staircase is concrete slab. Foundation is on piles. Infill vertical structures are brick. In the fifth floor pool is located.
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Relevance of the hydrostatic and hydrodynamic paradox
Vacula, Jiří ; Haluza, Miloslav (referee) ; Fialová, Simona (advisor)
This bachelor’s thesis is concerned with the explanation of the hydrostatic and hydrodynamic paradox existence. Above all hydrostatic paradox is not in general properly explained which causes additional puzzle. Therefore the aim of this thesis is to find real reasons of these effects and in addition to check up possible consequences of liquid compressibility.
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