Speaker
Description
The current quest for spintronic devices might benefit from taking advantage of the properties of highly perfect materials. For example, spinels are oxides with interesting properties that suggest many possible applications based on them. However, growth defects are ubiquitous in spinel thin films. A possible path to obtain highly perfect spinel nanostructures is through growth by oxygen assisted molecular beam epitaxy stopping the growth before island coalescence, where each spinel crystal arises from a single nucleus. We have successfully employed it to grown various spinel oxides on Ru(0001) single crystals and films, including mixed Ni-Fe [1] and Co-Fe spinels [2]. In particular we have used low-energy electron microscopy to follow the growth at several Co/Fe ratios, complementing it with x-ray absorption spectroscopy analysis of the grown films [3]. However, in a complex multicomponent system, LEEM cannot track the composition evolution of the growth front. In order to follow that evolution, we have acquired PEEM images during the growth at Fe and Co L23 edges by means of photoemission electron microscopy [4]. In this way, we have seen how the composition of the different phases present in the films evolve with coverage.
This work is supported by the Grants RTI2018-095303-B-C51, -A-C52 and -B-C53 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”, and by the Grant S2018-NMT-4321 funded by the Comunidad de Madrid and by “ERDF A way of making Europe”. C.G.-M. and A.Q. acknowledge financial support from the Spanish Ministerio de Ciencia e Innovación (MICINN) through the “Juan de la Cierva” Program (FJC2018-035532-I) and the “Ramón y Cajal” Contract (RYC-2017-23320), respectively. The experiments were performed at the LEEM microscope at IQFR, CSIC, acquired with funds from the Spanish Ministerio de Economía, Industria y Competitividad (MINECO) through project CSIC15-EE-3056 and the
European Regional Development Fund (ERDF), and at the PEEM station of CIRCE beamline of the Alba synchrotron.
[1] A. Mandziak, J. de la Figuera, S. Ruiz-Gómez, G. D. Soria, L. Pérez, P. Prieto, A. Quesada, M. Foerster, and L. Aballe, Structure and Magnetism of Ultrathin Nickel-Iron Oxides Grown on Ru(0001) by High-Temperature Oxygen-Assisted Molecular Beam Epitaxy, Sci. Rep. 8, 17980 (2018).
[2] L. Martín-García, A. Quesada, C. Munuera, J. F. Fernández, M. García-Hernández, M. Foerster, L. Aballe, and J. de la Figuera, Atomically Flat Ultrathin Cobalt Ferrite Islands, Adv. Mater. 27, 5955 (2015).
[3] L. Martín-García, A. Quesada, L. Pérez, M. Foerster, L. Aballe, and J. de la Figuera, Initial Stages of the Growth of Mixed Iron-Cobalt Oxides on Ru(0001), Physics Procedia 85, 12 (2016).
[4] S. Ruiz-Gomez, A. Mandziak, J. E. Prieto, M. Aristu, E. M. Trapero, G. D. Soria, A. Quesada, M. Foerster, L. Aballe, and J. de la Figuera, A Real-Time XAS PEEM Study of the Growth of Cobalt Iron Oxide on Ru(0001), Journal of Chemical Physics 152, (2020).
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