Spin-resolved low-energy and hard x-ray photoelectron spectroscopy of off-stoichiometric Co2MnSi Heusler thin films exhibiting a record TMR

Fetzer R, Ouardi S, Honda Y, Liu HX, Chadov S, Balke B, Ueda S, Suzuki M, Uemura T, Yamamoto M, Aeschlimann M, Cinchetti M, Fecher GH, Felser C (2015)

Publication Type: Journal article

Publication year: 2015

Journal

Journal of Physics D: Applied Physics IOP Publishing: Hybrid Open Access

Book Volume: 48

Article Number: 164002

Journal Issue: 16

DOI: 10.1088/0022-3727/48/16/164002

Abstract

Half-metallic Co2MnSi-based Heusler compounds have attracted attention because they yield very high tunnelling magnetoresistance (TMR) ratios. Record TMR ratios of 1995% (at 4.2 K) are obtained from off-stoichiometric Co2MnSi-based magnetic tunnel junctions. This work reports on a combination of band structure calculations and spin-resolved and photon-polarisation-dependent photoelectron spectroscopy for off-stoichiometric Heusler thin films with the composition Co2Mn1.30Si0.84. Co and Mn are probed by magnetic dichroism in angle-resolved photoelectron spectroscopy at the 2p core level. In contrast to the delocalised Co 3d states, a pronounced localisation of the Mn 3d states is deduced from the corresponding 2p core level spectra. The valence states are investigated by linear dichroism using both hard x-ray and very-low-photon-energy excitation. When a very low photon energy is used for excitation, the valence bands exhibit a spin polarisation of about 30% at the Fermi energy. First principles calculations reveal that the low spin polarisation might be caused by a spin-flip process in the photoelectron final states.

Involved external institutions

Technische Universität Kaiserslautern DE Germany (DE) Max-Planck-Institut für Chemische Physik fester Stoffe (MPI CPfS) / Max Planck Institute for Chemical Physics of Solids DE Germany (DE) Hokkaido University (Hokudai) / 北海道大学 JP Japan (JP) Johannes Gutenberg-Universität Mainz (JGU) DE Germany (DE) National Institute of Materials Science (NIMS) JP Japan (JP) Japan Synchrotron Radiation Research Institute (JASRI) JP Japan (JP)

How to cite

APA:

Fetzer, R., Ouardi, S., Honda, Y., Liu, H.-X., Chadov, S., Balke, B.,... Felser, C. (2015). Spin-resolved low-energy and hard x-ray photoelectron spectroscopy of off-stoichiometric Co2MnSi Heusler thin films exhibiting a record TMR. Journal of Physics D: Applied Physics, 48(16). https://doi.org/10.1088/0022-3727/48/16/164002

MLA:

Fetzer, Roman, et al. "Spin-resolved low-energy and hard x-ray photoelectron spectroscopy of off-stoichiometric Co2MnSi Heusler thin films exhibiting a record TMR." Journal of Physics D: Applied Physics 48.16 (2015).

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