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MA: Fachverband Magnetismus

MA 41: Micromagnetism / Computational Magnetics

MA 41.8: Vortrag

Mittwoch, 22. März 2017, 17:00–17:15, HSZ 101

Size-induced changes of structural and ferromagnetic properties in La_1-xSr_SrMnO₃ nanoaparticles — •Cornelia Hintze¹, Dirk Fuchs¹, Michael Merz^1,2, Houari Amari³, Christian Kübel^2,3, Meng-Jie Huang¹, Annie Powell^3,4, and Hilbert von Löhneysen¹ — ¹Karlsruhe Institut für Technologie, Institut für Festkörperphysik, 76021 Karlsruhe — ²Karlsruhe Institut für Technologie, Karlsruhe Nano Micro Facility, 76021 Karlsruhe — ³Karlsruhe Institut für Technologie, Institut für Nanotechnologie, 76021 Karlsruhe — ⁴Karlsruhe Institut für Technologie, Institut für Anorganische Chemie, 76021 Karlsruhe

La_1-xSr_xMnO₃ nanoparticles (NP) were grown by microemulsion, with Sr concentrations from x=0.35 to 0.50 and diameters between 20 and 40 nm. This technique allows the controlled growth of structurally well-defined NP in a range of sizes using the same preparation conditions. With decreasing particle size, the unit cell volume and the Mn-O bond length increase, while the Mn-O-Mn bond angle decreases. The size-dependent change of structural properties is possibly related to surface effects or disorder. With the decrease of NP size the ferromagnetic ordering temperature T_C decreases by up to 20%. The reduction of T_C can be understood with respect to structural changes: the increase of Mn-O bond length and decrease of Mn-O-Mn bond angle weaken the double-exchange coupling and hence reduce T_C. In addition the intrinsic finite-size effect reduces T_C. The observed size-induced change of magnetic properties may allow for a controlled manipulation of magnetism in La_1-xSr_xMnO₃ NP by varying NP size.