Improved interfacial local structural ordering of epitaxial Fe3Si(001) thin films on GaAs(001) by a MgO(001) tunneling barrier

Makarov, Igor; Krumme, B.; Stromberg, F.; Weis, C.; Keune, W.; Wende, Heiko

doi:10.1063/1.3646390

Cited by 12 publications

(6 citation statements)

References 17 publications

(25 reference statements)

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“…One important aspect of Mössbauer spectroscopy is its sensitivity to chemical ordering processes at the atomic scale in magnetic alloys. Mössbauer spectroscopy can contribute to the characterization and development of Mössbauer-isotope containing chemically ordered thin-film Heusler alloys [6,23,24,28,29], which are important electron spin injectors, e.g. for GMR, TMR or spin-optoelectronics devices, due to their anticipated huge electronic spin polarization at the Fermi energy.…”

Section: Discussionmentioning

confidence: 99%

“…In this respect, the Mössbauer effect is complementary to other powerful methods, like X-ray magnetic circular dichroism (XMCD) [22], which, however, provides the local atomic magnetic moment directly with high precision, and often enables to distinguish atomic orbital and spin magnetic moments of the electrons. On the other hand, magnetic properties of non-equivalent crystallographic sites (magnetic sublattices) in metallic alloys, as revealed by their different hyperfine fields, may be observed by Mössbauer spectroscopy [6,23,24], whereas such magnetic sublattices cannot be resolved by XMCD, and only the average atomic magnetic moment is measured by the latter technique [24]. It is well known that the hyperfine field and the Mössbauer isomer shift (chemical shift) both correlate with the chemical charge state of the Mössbauer atom.…”

Section: Introductionmentioning

confidence: 99%

“…This works reasonably well in those cases where the core-polarization contribution, B core , to the total hyperfine magnetic field, B hf , dominates over other contributions, as, for instance, the contribution from spin-polarized conduction electrons, B ce , (spin-polarized by magnetic atoms). As an example, let us consider the chemically ordered quasi-Heusler compound Fe 3 Si with the D0 3 structure, where two inequivalent Fe lattice sites exist [23,24]: Fe(D) sites with B hf (D) = 30.8 T and Fe(A) sites with B hf (A) = 20 T, and corresponding Fe atomic moments of μ Fe (D) = 2.2 μ B and μ Fe (A) = 1.35 μ B , as determined by magnetic neutron scattering [32]. This results in a ratio of 14.0 T/μ B for the D site and 14.8 T/μ B for the A site, i.e., in a deviation of ∼6%.…”

Section: Introductionmentioning

confidence: 99%

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Application of Mössbauer spectroscopy in magnetism

Keune

2012

Hyperfine Interact

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An overview is provided on our recent work that applies 57 Fe Mössbauer spectroscopy to specific problems in nanomagnetism. 57 Fe conversion electron Möss-bauer spectroscopy (CEMS) in conjunction with the 57 Fe probe layer technique as well as 57 Fe nuclear resonant scattering (NRS) were employed for the study of various nanoscale layered systems: (i) metastable fct-Fe; a strongly enhanced hyperfine magnetic field B hf of ∼39 T at 25 K was observed in ultrahigh vacuum (UHV) on uncoated three-monolayers thick epitaxial face-centered tetragonal (fct) 57 Fe(110) ultrathin films grown by molecular-beam epitaxy (MBE) on vicinal Pd(110) substrates; this indicates the presence of enhanced Fe local moments, μ Fe , as predicted theoretically; (ii) Fe spin structure; by applying magnetic fields, the Fe spin structure during magnetization reversal in layered (Sm-Co)/Fe exchange spring magnets and in exchange-biased Fe/MnF 2 bilayers was proven to be non-collinear and depth-dependent; (iii) ferromagnet/semiconductor interfaces for electrical spin injection; CEMS was used as a diagnostic tool for the investigation of magnetism at the buried interface of Fe electrical contacts on the clean surface of GaAs(001) and GaAs(001)-based spin light-emitting diodes (spin LED) with in-plane or out-ofplane Fe spin orientation; the measured rather large average hyperfine field of ∼27 T at 295 K and the distribution of hyperfine magnetic fields, P(B hf ), provide evidence for the absence of magnetically "dead" layers and the existence of relatively large Fe moments (μ Fe ∼ 1.8 μ B ) at the ferromagnet/semiconductor interface. -Finally, a short outlook is given for potential applications of Mössbauer spectroscopy on topical subjects of nanomagnetism/spintronics.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Application of Mössbauer spectroscopy in magnetism

Keune

2012

Hyperfine Interact

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“…[10][11][12] The undesirable interdiffusion at the FM/SC interface can be eliminated by MgO interlayers as it has been shown, e.g., for the material system FM/MgO/GaAs. 13,14 Further advantages of MgO interlayers are their suitability as tunnel barriers, and also their usability as spin filters, in particular for nonhalfmetallic FM contacts. 15,16 Nonetheless, the spin generation in FM/MgO/SC tunnel contacts might be affected by FM and oxygen intermixing at the new FM/MgO interface when using non-epitaxially deposited MgO films 17 , as well as by oxygen vacancies in the MgO layer 18 even during epitaxial growth.…”

Section: Introductionmentioning

confidence: 99%

Spin generation in completely MBE-grown Co2FeSi/MgO/GaAs lateral spin valves

Hoffmann

Herfort

Ramsteiner

2019

Phys. Rev. Materials

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We demonstrate first measurements of successful spin generation in crystalline Co 2 FeSi/MgO/GaAs hybrid structures grown by molecular-beam epitaxy (MBE), with different MgO interlayer thicknesses. Using non-local spin valve and non-local Hanle measurement configurations, we determine spin lifetimes of τ ≈ 100 ns and spin diffusion lengths of λ ≈ 5.6 µm for different MgO layer thicknesses proving the high quality of the GaAs transport channel. For an optimized MgO layer thickness, the bias dependence of the spin valve signals indicates the verification of the half-metallic gap (upper edge) of Co 2 FeSi in accordance with first principle calculations. In addition to that, spin generation efficiencies up to 18% reveal the high potential of MgO interlayers at the Co 2 FeSi/GaAs interface for further device applications. * ramsteiner@pdi-berlin.de

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“…12 Work on Fe x Si 1-x thin films to date has focused on the chemically ordered endpoints of the composition range near x=0.75 or 0.5. 13,14,15,16,17 Berling et. al.…”

Section: Introductionmentioning

confidence: 99%