DPG Phi
Verhandlungen
Verhandlungen
DPG

Berlin 2012 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

MA: Fachverband Magnetismus

MA 33: Magnetic Coupling Phenomena/ Exchange Bias

MA 33.7: Talk

Wednesday, March 28, 2012, 17:00–17:15, EB 202

Magnetic exchange interactions in perovskites ATcO3 (A = Ca, Sr, Ba) with high Neel temperature studied from first principles — •Vladislav Borisov1, Igor Maznichenko2, Sergey Ostanin1, Arthur Ernst1, and Ingrid Mertig1,21Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany — 2Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, D-06099 Halle, Germany

An extraordinary high Neel temperature (TN) has been found for the 4d transition metal oxides ATcO3 (A = Ca, Sr, Ba) with the perovskite structure. The magnetic properties and the exchange interactions in the system were studied from first principles using the KKR-CPA method based on the multiple-scattering theory. For each perovskite, the most preferable magnetic configuration was found to be G-type antiferromagnetic with antiparallel alignment of the neighboring magnetic moments. The observed magnetic ordering is accounted for by the strong superexchange interaction between the Tc cations which is mediated by a pronounced overlap of the technetium 4d orbitals and oxygen p orbitals. We obtained the values of the Neel temperature TN of 840 K for CaTcO3 and 930 K for SrTcO3 which are in a good agreement with the recent experiments. For BaTcO3 which is not available so far, we predict the fundamental band gap of 0.3 eV and TN ≈ 1000 K. In general, an increase in the volume leads to a noticeable enhancement of TN whereas the presence of vacancies on both the oxygen and Tc sites significantly lowers the critical temperature as well as the magnetic moments of Tc cations.

100% | Mobile Layout | Deutsche Version | Contact/Imprint/Privacy
DPG-Physik > DPG-Verhandlungen > 2012 > Berlin