[Zurück]

M. Küpferling, R. Grössinger, M. Pieper, G. Wiesinger, H. Michor, C. Ritter, F. Kubel:
"Structural phase transition and magnetic anisotropy of La-substituted M-type Sr hexaferrite";
Physical Review B, 73 (2006), S. 144408-1 - 144408-11.

Structural phase transition and magnetic anisotropy of La-substituted M-type Sr hexaferrite

Michaela Küpferling, Roland Grössinger, Martin W. Pieper, Günter Wiesinger, and Herwig Michor
Department of Solid State Physics, Vienna University of Technology, A-1040 Vienna, Austria

Clemens Ritter
Institute Laue-Langevin, F-38042 Grenoble, France

Frank Kubel
Department of Chemical Technologies and Analytics, Vienna University of Technology, A-1060 Vienna, Austria

(Received 23 December 2005; published 7 April 2006)

La-substituted Sr hexaferrite with different La concentrations x were prepared and investigated in order to observe changes in magnetic and structural properties with the substitution. With diffraction methods a change in crystal structure below approximately 100 K from hexagonal with spacegroup P6₃/mmc to orthorhombic with spacegroup Cmcm was observed for the fully substituted La hexaferrite and attributed to a lattice distortion. A large increase in magnetocrystalline anisotropy of LaFe₁₂O₁₉ at low temperatures was confirmed by measurements and associated with the formation of an orbital momentum of Fe²⁺ together with the lattice distortion. The localization of the Fe²⁺ ion at the 2a site was determined from the Mössbauer spectrum, showing also an indication for an orbital momentum in the hyperfine field. In contrast, neither a structural phase transition nor the formation of Fe²⁺ was observed at x<1 in x-ray diffraction or NMR spectroscopy.

©2006 The American Physical Society

URL: http://link.aps.org/abstract/PRB/v73/e144408

doi:10.1103/PhysRevB.73.144408

PACS: 75.50.Bb, 75.30.Gw, 61.66.Fn, 64.70.Kb

http://aleph.ub.tuwien.ac.at/F?base=tuw01&func=find-c&ccl_term=AC05938236

http://dx.doi.org/10.1103/PhysRevB.73.144408