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Studium nových silně korelovaných elektronových sloučenin REnTIn3n+2
Bartha, Attila ; Kratochvílová, Marie (advisor) ; Pospíšil, Jiří (referee)
We have studied two different systems; RE2CoIn8 (RE = Pr, Nd, Dy) and CenTIn3n+2 (T = Pd, Pt; n = 2, 3). All compounds were prepared for the first time in the single crystalline form using the self-flux method. X-ray diffraction confirmed the tetragonal Ho2CoGa8 structure type for the RE2CoIn8 compounds and for the new phase Ce2TIn8. The novel phase Ce3PtIn11 adopts the structure of the Ce3PdIn11 compound, which represents a new structure type. Magnetic measurements revealed low anisotropy and the c-axis as the easy axis for all RE2CoIn8 compounds. Pr2CoIn8 is a paramagnet, while Nd2CoIn8 and Dy2CoIn8 order antiferromagnetically. Magnetization and specific heat measurements of Dy2CoIn8 revealed complex magnetic field-temperature phase diagram with various types of magnetic ordering. Specific heat measurements on multiphase Ce-Pd-In system revealed superconducting transition at Tc = 0.69 K arising from Ce2PdIn8 and another magnetic transition from Ce3PdIn11 at ~ 1.7 K. Ce3PdIn11 and Ce3PtIn11 compounds reveal two, probably magnetic transitions at T1 = 1.6 K, T2 = 1.45 K and T1 = 2.1 K and T2 = 2.0 K, respectively. Specific heat data qualifies both materials as heavy fermion compounds with γ = 290 mJ.mol-1 Ce K-2 and γ = 300 mJ.mol-1 Ce K-2 respectively.
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Magnetic study of layered tetragonal compounds based on rare earths and uranium
Bartha, Attila ; Hrůzová Kratochvílová, Marie (advisor)
We have studied the interplay between the layered crystal structure and the 5f magnetism in uranium-based tetragonal compounds UnTIn3n+2. Sin- gle crystals of U2RhIn8, URhIn5 and UIn3 were prepared by In self-flux method. The novel U2RhIn8 compound adopts the Ho2CoGa8-type struc- ture with lattice parameters a = 4.6056(6) ˚A and c = 11.9911(15) ˚A. The behavior of U2RhIn8 strongly resembles that of related URhIn5 and UIn3 with respect to magnetization, specific heat and electrical resistivity except for magnetocrystalline anisotropy developing on stacking composition in the series UIn3 vs. U2RhIn8 and URhIn5. U2RhIn8 orders antiferromagnetically below TN = 117 K and exhibits slightly enhanced Sommerfeld coefficient γ = 47 mJ·mol−1 ·K−2 . TN increases with increasing c/a ratio in contrast to the behavior of their CenTIn3n+2 counterparts. Magnetic field leaves the value of the Néel temperature of URhIn5 and U2RhIn8 unaffected up to 9 T. On the other hand, TN increases with applied hydrostatic pressure up to 3.2 GPa with the ∂TN/∂p coefficient resembling URhIn5 and UIn3. Ther- mal expansion of U2RhIn8 reveals a hysteretic behavior of the antiferromag- netic transition pointing to its 1st -order character. The magnetic structure of URhIn5 obtained from neutron diffraction propagates with k = (1 /2, 1 /2, 1 /2) and the...
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Ground state investigations of Ce and U intermetallic compounds
Bartha, Attila ; Prokleška, Jan (advisor) ; Detlefs, Blanka (referee) ; Michor, Herwig (referee)
Title: Ground state investigations of Ce and U intermetallic compounds Author: Attila Bartha Department: Department of Condensed Matter Physics Supervisor: RNDr. Jan Prokleška, Ph.D., Department of Condensed Matter Physics Abstract: Rare earth and actinide intermetallic compounds offer a plethora of interesting physical properties due to the varied behavior of f -electrons together with numerous interactions these electrons are exposed to. In this thesis we address a broad spectrum of ground state investigations on CePd2X3 (X=Zn, Ga) and (Ce,U)nTIn3n+2 (T=Rh, Ir) compounds. Single crystals of CePd2Zn3 and CePd2Ga3 compounds were synthesized for the first time using Bridgman method. CePd2Ga3 revealed a ferromagnetic transition with TC = 6.7 K with a strong magnetocrystalline anisotropy. CePd2Zn3 orders antiferromagnetically below TN = 1.9 K. Results of magnetization measurements on Ce2IrIn8 revealed effective magnetic moment µeff = 2.45µB/Ce3+ and a paramagnetic Curie temperature θP = −31 K. Decomposition of Hall resistivity ρxy(B) into NHE and AHE revealed a predom- inance of AHE in the temperature range from 60 K up to 100 K. Ce2RhIn8 was studied by means of magnetic field and angle dependent magnetization and heat capacity measurements. The resulting phase diagram reveals a complete unfold- ing and...
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Magnetic study of layered tetragonal compounds based on rare earths and uranium
Bartha, Attila ; Hrůzová Kratochvílová, Marie (advisor)
We have studied the interplay between the layered crystal structure and the 5f magnetism in uranium-based tetragonal compounds UnTIn3n+2. Sin- gle crystals of U2RhIn8, URhIn5 and UIn3 were prepared by In self-flux method. The novel U2RhIn8 compound adopts the Ho2CoGa8-type struc- ture with lattice parameters a = 4.6056(6) ˚A and c = 11.9911(15) ˚A. The behavior of U2RhIn8 strongly resembles that of related URhIn5 and UIn3 with respect to magnetization, specific heat and electrical resistivity except for magnetocrystalline anisotropy developing on stacking composition in the series UIn3 vs. U2RhIn8 and URhIn5. U2RhIn8 orders antiferromagnetically below TN = 117 K and exhibits slightly enhanced Sommerfeld coefficient γ = 47 mJ·mol−1 ·K−2 . TN increases with increasing c/a ratio in contrast to the behavior of their CenTIn3n+2 counterparts. Magnetic field leaves the value of the Néel temperature of URhIn5 and U2RhIn8 unaffected up to 9 T. On the other hand, TN increases with applied hydrostatic pressure up to 3.2 GPa with the ∂TN/∂p coefficient resembling URhIn5 and UIn3. Ther- mal expansion of U2RhIn8 reveals a hysteretic behavior of the antiferromag- netic transition pointing to its 1st -order character. The magnetic structure of URhIn5 obtained from neutron diffraction propagates with k = (1 /2, 1 /2, 1 /2) and the...
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Studium magnetismu vrstevnatých tetragonálních sloučenin na bázi vzácných zemin a uranu
Bartha, Attila ; Hrůzová Kratochvílová, Marie (advisor) ; Prokleška, Jan (referee)
We have studied the interplay between the layered crystal structure and the 5f magnetism in uranium-based tetragonal compounds UnTIn3n+2. Sin- gle crystals of U2RhIn8, URhIn5 and UIn3 were prepared by In self-flux method. The novel U2RhIn8 compound adopts the Ho2CoGa8-type struc- ture with lattice parameters a = 4.6056(6) ˚A and c = 11.9911(15) ˚A. The behavior of U2RhIn8 strongly resembles that of related URhIn5 and UIn3 with respect to magnetization, specific heat and electrical resistivity except for magnetocrystalline anisotropy developing on stacking composition in the series UIn3 vs. U2RhIn8 and URhIn5. U2RhIn8 orders antiferromagnetically below TN = 117 K and exhibits slightly enhanced Sommerfeld coefficient γ = 47 mJ·mol−1 ·K−2 . TN increases with increasing c/a ratio in contrast to the behavior of their CenTIn3n+2 counterparts. Magnetic field leaves the value of the Néel temperature of URhIn5 and U2RhIn8 unaffected up to 9 T. On the other hand, TN increases with applied hydrostatic pressure up to 3.2 GPa with the ∂TN/∂p coefficient resembling URhIn5 and UIn3. Ther- mal expansion of U2RhIn8 reveals a hysteretic behavior of the antiferromag- netic transition pointing to its 1st -order character. The magnetic structure of URhIn5 obtained from neutron diffraction propagates with k = (1 /2, 1 /2, 1 /2) and the...
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Studium nových silně korelovaných elektronových sloučenin REnTIn3n+2
Bartha, Attila ; Kratochvílová, Marie (advisor) ; Pospíšil, Jiří (referee)
We have studied two different systems; RE2CoIn8 (RE = Pr, Nd, Dy) and CenTIn3n+2 (T = Pd, Pt; n = 2, 3). All compounds were prepared for the first time in the single crystalline form using the self-flux method. X-ray diffraction confirmed the tetragonal Ho2CoGa8 structure type for the RE2CoIn8 compounds and for the new phase Ce2TIn8. The novel phase Ce3PtIn11 adopts the structure of the Ce3PdIn11 compound, which represents a new structure type. Magnetic measurements revealed low anisotropy and the c-axis as the easy axis for all RE2CoIn8 compounds. Pr2CoIn8 is a paramagnet, while Nd2CoIn8 and Dy2CoIn8 order antiferromagnetically. Magnetization and specific heat measurements of Dy2CoIn8 revealed complex magnetic field-temperature phase diagram with various types of magnetic ordering. Specific heat measurements on multiphase Ce-Pd-In system revealed superconducting transition at Tc = 0.69 K arising from Ce2PdIn8 and another magnetic transition from Ce3PdIn11 at ~ 1.7 K. Ce3PdIn11 and Ce3PtIn11 compounds reveal two, probably magnetic transitions at T1 = 1.6 K, T2 = 1.45 K and T1 = 2.1 K and T2 = 2.0 K, respectively. Specific heat data qualifies both materials as heavy fermion compounds with γ = 290 mJ.mol-1 Ce K-2 and γ = 300 mJ.mol-1 Ce K-2 respectively.
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