|
|
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...
|
|
|
Nanopowders of R.sub.2./sub.Fe.sub.14./sub.B-type compounds in high magnetic fields: The effects of substitutional and interstitial atoms on inter-sublattice exchange interaction
Paukov, M. ; Ivanov, L. ; Tereshina, I. ; Tereshina-Chitrova, Evgenia ; Gorbunov, D. ; Andreev, A. V. ; Pyatakov, A.P. ; Granovsky, S.A. ; Doerr, M. ; Drulis, H.
The fundamental magnetic characteristics of R2Fe14B intermetallics are highly sensitive to atomic substitutions and interstitial absorption of light elements. In this work, both were combined, and the influence of the substitutions in the R-sublattice and hydrogen absorption on the magnetization of (RR’) 2Fe14BHx (R is Tm or Er, and R’ is Nd) in magnetic fields up to 58 T was studied. By using direct hydrogen absorption, (R0.5Nd0.5)2Fe14BHx compounds were obtained with hydrogen content 0≤x≤5.5. Magnetic measurements were carried out on nanopowders. The strength of the inter-sublattice coupling in (R0.5Nd0.5)2Fe14B and their hydrides is estimated by analysing high-field magnetization data. It is shown that hydrogenation weakens the inter-sublattice exchange interaction up to 45 %.
|
|
|
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.