Type of presentation: Poster

MS-12-P-2036 Chemical and Defect Analysis in a ZrO2/LSMO Pillar-Matrix System

Zhou D.1, Sigle W.1, Wang Y.1, Kelsch M.1, Gao Y.2, Habermeier H.2, van Aken A. P.1
1Max Planck Institute for Intelligent Systems, Stuttgart Center for Electron Microscopy, Stuttgart, Germany , 2Max Planck Institute for Solid State Research, Stuttgart, Germany
danzhou@is.mpg.de

Recently there has been tremendous research on self-assembled vertically aligned nanocomposite thin films with two immiscible components hetero-epitaxially grown on single crystal substrates1-4. These structures have the advantages of utilizing both component functions and tuning material properties with high interface-to-volume ratio, hetero-epitaxial strain, or modifying the cation valence state.

Here we report about the characterization of self-assembled vertically aligned non-magnetic zirconium oxide (ZrO2) and ferromagnetic perovskite lanthanum strontium manganese oxide (La2/3Sr1/3MnO3, LSMO) pillar-matrix nanostructures, which are epitaxially grown on (001) single-crystalline lanthanum aluminum oxide (LaAlO3, LAO) substrate by pulsed laser deposition. With the application of electron energy-loss spectroscopy (EELS) in a probe-aberration-corrected JEOL JEM-ARM200CF, atomic resolution elemental distribution, including La, Sr, Mn, and Zr, as shown in Figure 1, and the Mn valence state variation at the interface between LSMO and ZrO2 were observed. In addition, Mn-rich walls were found connecting adjacent pillars. The crystal lattices on either side of the wall are displaced by an antiphase shift as can be seen in Figure 2. The Mn valence state in the channel was found to be decreased compared to the matrix. The wall plane is {110} or {130}. The role of the pillars and walls regarding elastic strain and local electric fields will be discussed.

The spin, charge, and orbital ordering in LSMO are extremely sensitive to local structural and elemental variations. Thus, these results provide the basis for understanding the origin of the anomalous magnetic anisotropy and modifications to the electric transport properties of LSMO by introducing non-magnetic ZrO2 pillars5-7.

References:

1. Chen et.al., Nanotechnology 2011, 22, (31).

2. Imai et.al., Acs Nano 2013, 7, (12), 11079-11086.

3. Zheng et.al., Nano Lett 2006, 6, (7), 1401-1407.

4. Liu et.al., Acs Nano 2012, 6, (8), 6952-6959.

5. Gao et.al., Prog Nat Sci-Mater 2013, 23, (2), 127-132.

6. Jin et.al., J. C. J Supercond Nov Magn 2013, 26, (5), 1621-1624.

7. Gao et.al., Solid State Commun 2013, 154, 46-50.

The research leading to these results has received funding from the European Union Seventh Framework Program [FP/2007-2013] under grant agreement no 312483 (ESTEEM2).

Fig. 1: Annular dark-field (a) and elemental distribution ((b) Sr L, (c) La M, (d) Mn L, (e) Zr L) images extracted from EELS spectrum images.

Fig. 2: (a) HAADF image of ZrO2 pillars and LSMO matrix. (b) Enlargement of a Mn-rich wall with annotations of the wall plane.