|
|
Magnetic and magnetoelastic properties of f-d intermetallics with high content of 3d-metal
Gorbunov, Denis ; Andreev, Alexander (advisor) ; Kamarád, Jiří (referee) ; Svoboda, Pavel (referee)
Fundamental magnetic properties have been studied in RFexAl12-x (R - heavy rare-earth element) compounds with the tetragonal crystal structure of the ThMn12 type. In the homogeneity range 4 ≤ x ≤ 6, exchange interactions and magnetocrystalline anisotropy of the Fe sublattice are significantly modified as found in LuFexAl12-x with non-magnetic Lu. With increasing Fe content, antiferromagnetic exchange interactions weaken and ferromagnetic strengthen. The change of the type of magnetic ordering occurs in the vicinity of x = 5. The Fe sublattice displays an easy-plane magnetic anisotropy that weakens with growing Fe concentration. RFe5Al7 compounds with magnetic R are highly anisotropic ferrimagnets with Curie temperatures from 193 to 262 K. Spontaneous and field-induced magnetic phase transitions of anisotropic and exchange nature have been found in RFe5Al7 by measurements of magnetization and sound propagation. The transitions provide quantitative information on the R-Fe inter-sublattice exchange. A correlation between the R element and the fundamental magnetic properties has been found for RFe5Al7. The Fe magnetic moment is near 8 µB per formula unit. The compounds with R - Tb, Dy, Ho and Er have a compensation of the rare- earth and iron sublattice magnetizations. The compensation point and Curie...
|
|
| |
|
| |
|
| |
|
| |
|
|
Physical phenomena in ytterbium- and cerium-based compounds
Fikáček, Jan ; Sechovský, Vladimír (advisor) ; Arnold, Zdeněk (referee) ; Andreev, Alexander (referee)
This work contains a study of CeRuSn, which undergoes two structural transitions at 290 K and 256 K both connected with large temperature hysteresis. During the transitions the lattice shrinks along the c axis. At low temperatures the compound orders antiferromagnetically below 2.8(1) K. A strong magnetocrystalline anisotropy is caused by very shortened Ce-Ru separations pointing approximately along the c axis. Due to a strong hybridization, two thirds of Cerium atoms are in a non integer valence state. For the first time synthesized single-crystals of YbPt2Si2 a Yb2Pt3Si5 show no magnetic ordering. A maximum, which is visible in the temperature dependences of magnetic susceptibility originate in thermal population of the magnetic Yb3+ state. Powered by TCPDF (www.tcpdf.org)
|
|
|
Magnetic and magnetoelastic properties of f-d intermetallics with high content of 3d-metal
Gorbunov, Denis ; Andreev, Alexander (advisor) ; Kamarád, Jiří (referee) ; Svoboda, Pavel (referee)
Fundamental magnetic properties have been studied in RFexAl12-x (R - heavy rare-earth element) compounds with the tetragonal crystal structure of the ThMn12 type. In the homogeneity range 4 ≤ x ≤ 6, exchange interactions and magnetocrystalline anisotropy of the Fe sublattice are significantly modified as found in LuFexAl12-x with non-magnetic Lu. With increasing Fe content, antiferromagnetic exchange interactions weaken and ferromagnetic strengthen. The change of the type of magnetic ordering occurs in the vicinity of x = 5. The Fe sublattice displays an easy-plane magnetic anisotropy that weakens with growing Fe concentration. RFe5Al7 compounds with magnetic R are highly anisotropic ferrimagnets with Curie temperatures from 193 to 262 K. Spontaneous and field-induced magnetic phase transitions of anisotropic and exchange nature have been found in RFe5Al7 by measurements of magnetization and sound propagation. The transitions provide quantitative information on the R-Fe inter-sublattice exchange. A correlation between the R element and the fundamental magnetic properties has been found for RFe5Al7. The Fe magnetic moment is near 8 µB per formula unit. The compounds with R - Tb, Dy, Ho and Er have a compensation of the rare- earth and iron sublattice magnetizations. The compensation point and Curie...
|
|
| |
|
| |
|
| |
guest ::
RSS feed.