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O: Fachverband Oberflächenphysik

O 32: Oxides and Insulators: Clean Surfaces

O 32.6: Vortrag

Dienstag, 26. Februar 2008, 14:15–14:30, MA 042

Electronic structure and thermodynamic stability of cubic La_xSr_1−xMnO₃ (001) surfaces: First-principles calculations by means of hybrid density-functional theory — •Sergejs Piskunovs¹, Eckhard Spohr¹, and Timo Jacob² — ¹Lehrstuhl fuer Theoretische Chemie, Universitaet Duisburg-Essen, Campus Essen, S05 V06 E15, Universitaetsstr. 5, D-45141 Essen, Germany — ²Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin-Dahlem, Germany

Surface properties of La_xSr_1−xMnO₃ (LSM) are of high scientific and technological interest due to potential application of these materials in magnetoresistive devices, spintronics, and high-temperature fuel cells. Using the hybrid exchange-correlation functional within density functional theory, we calculated the electronic structure for a wide range of cubic LSM(001) surfaces at low doping x∼ 1/8. The layered antiferromagnetic structure is found to be the most energetically favorable for all LSM(001) surfaces under study. Stability of the considered LSM surfaces has been predicted by means of the atomistic thermodynamics. Our calculations show that segregation of Sr at La(Sr)-terminated surface does not lead to its stabilization and thus is thermodynamically unlikely. On the other hand, MnO₂-terminated LSM(001) can be stabilized through adsorption of atomic oxygen atop of Mn sites.