guest ::
| Home > Publications database > Relation between deposition methods on magnetic depth profile of [La2/3Sr1/3]xMnyOz/SrTiO3 |
| Home > Publications database > Relation between deposition methods on magnetic depth profile of [La2/3Sr1/3]xMnyOz/SrTiO3 |
| Poster (After Call) | FZJ-2015-02964 |
; ; ; ; ; ;
2014
Abstract: In transition metal oxide thin films the exact control of stoichiometry can explain phenomena like ferromagnetism or superconductivity at interfaces of non-magnetic materials as found in LaAlO3/SrTiO3[1]. Here, we show the influence of growth modes on the magnetic depth profile of different [La2/3Sr1/3] to Mn ratios in thin [La2/3Sr1/3]x[Mn]y[O]z layers on SrTiO3 substrates via Polarized Neutron Reflectometry.Via oxide Molecular Beam Epitaxy, it is feasible to control not only the total stoichiometry of a sample but additionally master an individual stoichiometry for each atomic layer by individual operation of effusion cell shutters for different elements. While co-deposition of (La/Sr) and Mn lead to A site substitution of Mn in case of Mn excess [2] in the perovskite structure ABO3, with shuttered deposition it is feasible to grow different crystal structures like members of the Ruddlesden−Popper series [3]. We investigate this influence of nominally identical stoichiometries onto the magnetic depth profile via neutron reflectometry at TREFF@MLZ.Via two complementary methods the films with typically 20 nm thickness were prepared, on the one hand using conventional co-deposition (La, Sr, and Mn shutters opened and closed simultaneously), on the other hand via shuttered deposition (either La and Sr shutters open or Mn shutter open). The Reflection High Energy Electron Diffraction (RHEED) oscillations were monitored to optimize the opening periods of Mn shutter or (La/Sr) shutters.The stoichiometry of reference samples [La2/3Sr1/3]1[Mn]1[O]3 was verified via Rutherford Backscattering Spectroscopy (RBS). The growth rates for Mn, La and Sr were calibrated by quartz crystal balance. X-ray reflectivity measurements revealed for all films a roughness well below 1nm which indicates a smooth surface, via X-ray diffraction the out-of-plane lattice parameter was determined and therefore the oxygen saturation was verified [4]. The magnetic properties as function of varying the (La/Sr):Mn ratio were determined via SQUID. The ferromagnetic transition temperature shows a well-defined dependency as function of Mn content; with increasing Mn content the Curie temperature increases.References[1] M. Warusawithana et al., Nat. Commun. 4, 2351 (2013)[2] C. Aruta et al., Phys. Rev. B 86, 115132 (2012)[3] R. Palgrave et al., J. Am. Chem. Soc. 134, 7700 (2012)[4] P. Orgiani et al., Appl. Phys. Lett. 100, 042404 (2012)
Keyword(s): Key Technologies (1st) ; Information Technology and Functional Materials (1st) ; Condensed Matter Physics (2nd) ; Magnetism (2nd)
|
The record appears in these collections: |