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Interface-related magnetic and vibrational properties in Fe/MgO heterostructures from nuclear resonant spectroscopy and first-principles calculations

Eggert, Benedikt and Gruner, Markus E. and Ollefs, Katharina and Schuster, Ellen and Rothenbach, Nico and Hu, Michael Y. and Zhao, Jiyong and Toellner, Thomas S. and Sturhahn, Wolfgang and Pentcheva, Rossitza and Cuenya, Beatriz Roldan and Alp, Esen E. and Wende, Heiko and Keune, Werner (2020) Interface-related magnetic and vibrational properties in Fe/MgO heterostructures from nuclear resonant spectroscopy and first-principles calculations. Physical Review Materials, 4 (4). Art. No. 044402. ISSN 2475-9953. https://resolver.caltech.edu/CaltechAUTHORS:20200406-130706672

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Abstract

We combine ⁵⁷Fe Mössbauer spectroscopy and ⁵⁷Fe nuclear resonant inelastic x-ray scattering (NRIXS) on nanoscale polycrystalline [bcc−⁵⁷Fe/MgO] multilayers with various Fe-layer thicknesses and layer-resolved density-functional-theory (DFT)-based first-principles calculations of a (001)-oriented [Fe(8 ML)/MgO(8 ML)](001) heterostructure (where ML denotes monolayer) to unravel the interface-related atomic vibrational properties of a multilayer system. Being consistent in theory and experiment, we observe enhanced hyperfine magnetic fields B_(hf) in the multilayers as compared to B_(hf) in bulk bcc Fe; this effect is associated with the Fe/MgO interface layers. NRIXS and DFT both reveal a strong reduction of the longitudinal acoustic phonon peak in combination with an enhancement of the low-energy vibrational density of states (VDOS) suggesting that the presence of interfaces and the associated increase in the layer-resolved magnetic moments results in drastic changes in the Fe-partial VDOS. From the experimental and calculated VDOS, vibrational thermodynamic properties have been determined as a function of Fe thickness and were found to be in excellent agreement.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1103/physrevmaterials.4.044402DOIArticle
ORCID:
AuthorORCID
Eggert, Benedikt0000-0001-7739-3541
Gruner, Markus E.0000-0002-2306-1258
Rothenbach, Nico0000-0002-2592-5857
Hu, Michael Y.0000-0002-3718-7169
Zhao, Jiyong0000-0002-0777-3626
Sturhahn, Wolfgang0000-0002-9606-4740
Alp, Esen E.0000-0002-4803-8863
Wende, Heiko0000-0001-8395-3541
Additional Information:© 2020 American Physical Society. Received 30 January 2020; accepted 5 March 2020; published 6 April 2020. We acknowledge funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation), Project No. 278162697-SFB 1242 (subprojects A05 and C02) and WE2623/14-1. We thank U. von Hörsten for his outstanding technical assistance and help for sample preparation. Calculations were carried out on the MagnitUDE supercomputer system (DFG Grants No. INST 20876/209-1 FUGG and No. INST 20876/243-1 FUGG). This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.
Funders:
Funding AgencyGrant Number
Deutsche Forschungsgemeinschaft (DFG)278162697-SFB 1242
Deutsche Forschungsgemeinschaft (DFG)WE2623/14-1
Deutsche Forschungsgemeinschaft (DFG)INST 20876/209-1 FUGG
Deutsche Forschungsgemeinschaft (DFG)INST 20876/243-1
Department of Energy (DOE)DE-AC02-06CH11357
Issue or Number:4
Record Number:CaltechAUTHORS:20200406-130706672
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200406-130706672
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:102354
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:06 Apr 2020 20:19
Last Modified:06 Apr 2020 20:19

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