Interface roughness in Fe(100)/Cr film structures studied by CEMS

Klinkhammer, F.; Sauer, Ch.; Tsymbal, E. Yu.; Handschuh, S.; Leng, Qunwen; Zinn, W.

doi:10.1016/s0304-8853(96)00063-7

Cited by 45 publications

(33 citation statements)

References 28 publications

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“…The wide distribution of hyperfine fields in the Fe/Cr case (as, e.g., for our Fe/Cr interface sample) occurs in random bulk Fe-Cr alloys [52] and near intermixed Fe/Cr interfaces [34,37,[48][49][50][51]. It is the existence of 57 Fe atoms with a distribution of local (atomic) magnetic moments [34,51] and with different local (atomic) environments near the alloyed Fe/Cr interface that leads to the apparent satellite lines in the Mössbauer spectra [ Fig.…”

Section: Local Environment Of Fe Atomsmentioning

confidence: 57%

“…[34], Fig. 2) (which gives information on the mesoscopic scale) of our epitaxial Fe(001)/Cr(001) multilayer center and interface samples provides evidence of the high-quality superlattice structure implying sharp interfaces on a mesoscopic scale, while CEMS (providing information on the atomic scale) demonstrates that the interfaces in the same Fe/Cr multilayer samples are not sharp but chemically intermixed [34,37,[48][49][50][51].Quantitatively, we measure that out of the 0.7-ML-thick 57 Fe probe layer at the Fe/Cr interface an equivalent of 0.55 ML of 57 Fe sense Cr atoms, whilst only 0.15 ML of 57 Fe do not interact with Cr atoms and have a bcc-Fe-type of local surroundings.…”

Section: Local Environment Of Fe Atomsmentioning

confidence: 70%

“…2(b)(i) on the right-hand side. The very wide P (B hf ) distribution is characterized by several peaks, i.e., several distinct 57 Fe sites, as a result of the interaction with nearest and next-nearest Cr atoms in the alloyed Fe/Cr interfacial region [34,37,[48][49][50][51]. Here, the average hyperfine field, B hf , averaged over the distribution P (B hf ), is found to be 22.2 T. It is interesting that small angle x-ray reflectometry (see Ref.…”

Section: Local Environment Of Fe Atomsmentioning

confidence: 99%

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Influence of interfaces on the phonon density of states of nanoscale metallic multilayers: Phonon confinement and localization

Keune

Hong

et al. 2018

Phys. Rev. B

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Isotope-selective 57 Fe nuclear resonant inelastic x-ray scattering (NRIXS) measurements and atomic-layer resolved density functional theory (DFT) calculations were used to investigate the effect of interfaces on the vibrational (phonon) density of states (VDOS) of (001)-oriented nanoscale Fe/Ag and Fe/Cr multilayers. The multilayers in the experiment contained isotopically enriched 57 Fe monolayers as probe layers located either at the Fe/Ag or Fe/Cr interfaces or in the center of the Fe films. This allows probing of the vibrational dynamics of Fe sites either at the buried interfaces or in the center of the Fe films. For Fe/Ag multilayers, distinct differences were observed experimentally between the Fe-partial VDOS at the interface and in the center. At the Fe/Ag interface, the high-energy longitudinal-acoustic (LA) phonon peak of Fe near ∼35 meV is suppressed and slightly shifted to lower energy, and the low-energy part of the VDOS below ∼20 meV is drastically enhanced, as compared to the Fe-specific VDOS in the center Fe layers or in bulk Fe. Similar phenomena are found to a less degree in the Fe/Cr multilayers. The measured Fe-partial VDOS was used to determine the Fe site-selective vibrational thermodynamic properties of the multilayers. Our theoretical findings for the layer-dependent VDOS of the multilayers are in qualitative agreement with the experimental results obtained by NRIXS. For Fe/Ag multilayers, which are characterized by a large atomic mass ratio, the experimental and theoretical results demonstrate phonon confinement in the Fe layers and phonon localization at the Fe/Ag interfaces due to the energy mismatch between Ag and Fe LA phonons. These phenomena are reduced or suppressed in the Fe/Cr multilayers with their about equal atomic masses. Moreover, direction-projected Fe VDOS along the (nearly in-plane) incident x-ray beam was computed in order to address the intrinsic vibrational anisotropy of the Fe/Ag multilayer. We have also performed spin-resolved electronic band structure (DFT) calculations, predicting an enhanced magnetic moment (μ Fe = 2.8 μ B ) of the interfacial Fe atoms and a high electron spin polarization (79%) at the Fermi energy for the Fe/Ag interface, as compared to the case of Fe center layers. This is a result of charge transfer from Fe to Ag at the interface. On the contrary, Cr tends to donate electrons to Fe, thus reducing the interfacial Fe moment (μ Fe = 1.9 μ B ). This implies strong chemical bonding at the Fe/Ag and Fe/Cr interfaces, affecting the interfacial VDOS.

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Section: Local Environment Of Fe Atomsmentioning

confidence: 57%

Section: Local Environment Of Fe Atomsmentioning

confidence: 70%

Section: Local Environment Of Fe Atomsmentioning

confidence: 99%

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Influence of interfaces on the phonon density of states of nanoscale metallic multilayers: Phonon confinement and localization

Keune

Hong

et al. 2018

Phys. Rev. B

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“…In this case a Brillouin function instead of the Langevin one was applied in model (2), to avoid too "soft" behavior at low temperatures.…”

Section: Mean Spin Evolutionmentioning

confidence: 99%

“…Magnetic hyperfine field distribution (HFD) is usually determined with the Mössbauer spectrometry and gives a valuable information on surface magnetic microstructure of thin layers [1][2][3], nanoparticles [4,5] and nanocrystalline alloys [6,7]. We have developed a basic model in order to predict temperature evolution of HFD corresponding to the surface of bcc Fe nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

Modeling of Magnetic Hyperfine Field Distribution for Spherical Nanoparticles of bcc Structure

et al. 2008

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We propose a simple model for temperature evolution of magnetic hyperfine field distribution of spherical bcc Fe nanoparticles. We performed mean field approximation calculations of mean spin value in each spherical shell of nanoparticle. Considering magnetic hyperfine field values reported for iron thin films we predicted possible values of hyperfine fields in the internal and surface region of the particles as a function of temperature.

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Structural and magnetic characterization of Fe/Cr/Fe tri‐layers and Fe/Cr multilayers after swift Au ion irradiation

Kąc

Dézsi

Toulemonde

et al. 2008

Physica Status Solidi (a)

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Fe/Cr/Fe trilayers and Fe/Cr multilayers were irradiated by 163 MeV Au ions with fluence of 1 × 1011 ions/cm2 to 50 × 1011 ions/cm2. The structural properties of Fe/Cr interfaces were observed using Conversion Electron Mössbauer Spectroscopy (CEMS) and X‐ray reflectivity (XRR). The magnetic exchange coupling between Fe layers through Cr spacer in trilayers and multilayers was determined from hysteresis loops measured with SQUID magnetometer. The different behavior of Fe/Cr/Fe trilayers and Fe/Cr multilayers was observed after Au ions irradiation. In Fe/Cr multilayers a decrease of the average value of hyperfine magnetic field with increasing Au ions fluence was observed, indicating an increase of the inter‐ increase of the interfacial roughness. In Fe/Cr/Fe trilayers the non‐monotonic behavior of average value of hyperfine magnetic field versus ion fluence was observed suggesting the smoothing of the interfaces at small fluences and roughening at higher ones. The smoothening of interfaces was confirmed by XRR spectra. In multilayers the magnetic properties changed in a similar way as the structural properties and continuous decay of antiferromagnetic coupling as a function of fluence was observed. In trilayers at the low fluences the antiferromagnetic coupling was not sensitive on irradiation, while at large fluences the decrease of antiferromagnetic coupling fraction was seen. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Interface roughness in Fe(100)/Cr film structures studied by CEMS

Cited by 45 publications

References 28 publications

Influence of interfaces on the phonon density of states of nanoscale metallic multilayers: Phonon confinement and localization

Influence of interfaces on the phonon density of states of nanoscale metallic multilayers: Phonon confinement and localization

Modeling of Magnetic Hyperfine Field Distribution for Spherical Nanoparticles of bcc Structure

Structural and magnetic characterization of Fe/Cr/Fe tri‐layers and Fe/Cr multilayers after swift Au ion irradiation

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