Dresden 2017 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 64: Poster 1

MA 64.13: Poster

Freitag, 24. März 2017, 09:30–13:00, P2-EG

Phase diagram of La_1−xSr_xMnO₃/SrTiO₃ epitaxial thin films — •Danny Schwarzbach¹, Markus Jungbauer², and Vasily Moshnyaga² — ¹Institut für Materialphysik, Georg-August-Universität Göttingen — ²Erstes Physikalisches Institut, Georg-August-Universität Göttingen

Charge, spin and orbital interface reconstructions in LaMnO₃/SrMnO₃ superlattices (SLs) result in a novel interfacial high-temperature ferromagnetism. We present a complex study of parent mixed-valence La_1−xSr_xMnO₃ (LSMO(x), x=0−1) film system, which enables us to model and quantify magnetic coupling between FM and AFM phases in SLs. The LSMO(x) films (d=40 nm) were epitaxially grown by metalorganic aerosol deposition technique on STO substrates with (001) and (111) orientations. The LSMO(x)/STO(001) films with x ≤ 0.6 were found to be fully strained, whereas those of LSMO(x)/STO(111) start to relax for x>0.4. The tensile strain in the (001)-plane favors an AFM ordering of the A-type due to orbital polarization of (x²−y²) orbitals of Mn ions. Therefore, the FM/AFM crossover is shifted to higher values of Sr-doping, x, for the films grown on STO(111) as compared to those on STO(001) substrate. Using in-situ optical ellipsometry we were able to monitor and control substrate temperature, film thickness and growth mode itself. Moreover, the acquired phase shift between p- and s-polarized reflected waves was found to depend on the charge density (Mn³⁺/Mn⁴⁺ ratio), helping us to quantify the FM/AFM crossover.

Financial support from DFG (SFB1073, TP B04) is acknowledged.