Hard X-ray photoelectron spectroscopy on buried, off-stoichiometric Co x Mn y Ge z (x:z=2:0.38) Heusler thin films

Ouardi S, Fecher GH, Chadov S, Balke B, Kozina X, Felser C, Taira T, Yamamoto M (2013)

Publication Type: Journal article

Publication year: 2013

Journal

Applied Physics A: Materials Science and Processing Springer Verlag (Germany)

Book Volume: 111

Pages Range: 395-405

Journal Issue: 2

DOI: 10.1007/s00339-013-7565-y

Abstract

Fully epitaxial magnetic tunnel junctions (MTJs) with off-stoichiometric Co2-based Heusler alloy shows an intense dependency of the tunnel magnetoresistance (TMR) on the Mn composition, demonstrating high TMR ratios of above 1000 % at 4.2 K (Yamamoto et al. J. Phys. Condens. Matter 22:164212, 2010). This work reports on the electronic structure of nonstoichiometric Co x Mn y Ge z thin films with a fixed Co/Ge ratio of x:z=2:0.38. The electronic structure was investigated by high-energy, hard X-ray photoelectron spectroscopy combined with first-principles calculations. The high-resolution measurements of the valence band of the nonstoichiometric Co x Mn y Ge z films close to the Fermi energy indicate a shift of the spectral weight compared to bulk Co2MnGe. This is in agreement with the changes in the density of states predicted by the calculations. Furthermore, it is shown that the co-sputtering of Co 2MnGe, together with additional Mn, is an appropriate technique to adjust the stoichiometry of the Co x Mn y Ge z film composition. The resulting changes of the electronic structure within the valence band will allow one to tune the magnetoresistive characteristics of Co x Mn y Ge z -based tunnel junctions as verified by the calculations and photoemission experiments. © 2013 Springer-Verlag Berlin Heidelberg.

Involved external institutions

Max-Planck-Institut für Chemische Physik fester Stoffe (MPI CPfS) / Max Planck Institute for Chemical Physics of Solids DE Germany (DE) Johannes Gutenberg-Universität Mainz (JGU) DE Germany (DE) Hokkaido University (Hokudai) / 北海道大学 JP Japan (JP)

How to cite

APA:

Ouardi, S., Fecher, G.H., Chadov, S., Balke, B., Kozina, X., Felser, C.,... Yamamoto, M. (2013). Hard X-ray photoelectron spectroscopy on buried, off-stoichiometric Co x Mn y Ge z (x:z=2:0.38) Heusler thin films. Applied Physics A: Materials Science and Processing, 111(2), 395-405. https://doi.org/10.1007/s00339-013-7565-y

MLA:

Ouardi, Siham, et al. "Hard X-ray photoelectron spectroscopy on buried, off-stoichiometric Co x Mn y Ge z (x:z=2:0.38) Heusler thin films." Applied Physics A: Materials Science and Processing 111.2 (2013): 395-405.

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