Interface-related magnetic and vibrational properties in Fe/MgO heterostructures from nuclear resonant spectroscopy and first-principles calculations
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.
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.Attached Files
Published - PhysRevMaterials.4.044402.pdf
Supplemental Material - suppl-Eggert-FeMgO.pdf
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Additional details
- Eprint ID
- 102354
- Resolver ID
- CaltechAUTHORS:20200406-130706672
- 278162697-SFB 1242
- Deutsche Forschungsgemeinschaft (DFG)
- WE2623/14-1
- Deutsche Forschungsgemeinschaft (DFG)
- INST 20876/209-1 FUGG
- Deutsche Forschungsgemeinschaft (DFG)
- INST 20876/243-1
- Deutsche Forschungsgemeinschaft (DFG)
- DE-AC02-06CH11357
- Department of Energy (DOE)
- Created
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2020-04-06Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field